We Finally Have A Planned Date For HF20! Changes Discussed..
Earlier today, 
Resource Credits vs Bandwidth Allocation
The Steem blockchain allows transactions (votes, posts, comments) for free, without paying some transaction fee each time (unlike Ethereum or Bitcoin). In an attempt to moderate the amount of transactions that are allowed per account, Steem has a bandwidth model that determines how many bytes of data an account can post to the blockchain. This is necessary because without it, users could post very large amounts of data that become a heavy burden on the servers maintaining the blockchain, aka witnesses.
In the new resource credits model, the calculations will be based on three aspects, blockchain size, state size, computational load, opposed to just the one, transaction size. The ultimate goal with this model is to more accurately represent the transaction cost imposed on the network. What this means in laymen's terms is basically when you look at more areas, you can get a better representation of the whole. The resource system hopes to use its knowledge of the current blockchain state to allocate the necessary credits to accounts.
Discounted Account Creation
As you may already be aware, Steem accounts have the ability to create more Steem accounts. If you signed up at https://steemit.com, you may not have even noticed that your account was actually created by 
account_create_with_delegation (and will be deprecated/removed with HF20). If you wanted to, you could use your own Steem account to create another account. This is a beautiful feature of Steem that allows developers to help contribute to the growth of the user base. However, you either have to spend 3 STEEM (at time of writing) or delegate about 15 SP when creating an account.
With Velocity (HF20), and the creation of resource credits, users will be able to use some of their resource credits to create accounts if they wish. The number of accounts they will be able to create depends on how much SP they have as well as some parameters set by the Steem Witnesses. Hopefully with this change, the user onboarding process will become much faster and reliable on SteemIt, leading to an almost instant growth of new users.
Account Creation Fees Burned
If an account is created absent of the resource credit system, the STEEM used to create the account will be burned instead of being deposited into the new account. This means that for every user account that is created with STEEM, the scarcity of STEEM increases potentially leading to higher STEEM prices. This change is something that most users will not need to worry much about, as it shouldn't change the user experience much.
Dust Vote Changes
This is a big one for new Steemians that have maybe yet to power up their SP. Previously, for an account to cast a vote, it needed to have a certain amount of SP powered up in the account. If the vote weight was too small, it would get rejected by the Steem network as a "dust vote". The reasoning for this was to prevent accounts from spamming tons of tiny votes that would minimal to no effect other than added resource demand on the network. With the addition of resource credits and the remove of the dust threshold, users will now be able to cast a vote no matter what (provided they have enough resource credits for their account.) This will lead to an enhanced user experience and less confusion amongst smaller accounts.
Removal of Minumum SP for Powering Down
Due to the previously mentioned fact that STEEM used for account creations will be burned into the 
Curation Updates
Currently, there is a period of time after a post is made where users, and bots, are disincentivized from voting. This period of time is 30 minutes long. The idea was that this would give humans a chance to properly read the post and decide on a vote to give without having to compete with bots or other users that only upvote in hopes of receiving more curation rewards. Although, the 30 minute window has been reduced to 15 minutes, the rest of the system largely remains the same.
Self-Voting Rewards
In the current system, if an author votes for their post immediately after posting it, they will receive the author rewards from their vote in addition to 100% of the curation rewards from that vote (as well as a percentage of curation rewards from every subsequent vote). This system highly incentivizes authors to vote their post immediately and prevents other users from having any chance of competing. With this change, the portion of the curation rewards not given to curators will actually be returned to the rewards pool, increasing the rewards for everyone.
Expiring Internal Market Orders
On the internal market, users are able to create orders that never have no chance of filling. This is unnecessary and causes undue strain on the blockchain. With HF20, market orders will now expire after 28 days. This is great news; though most users will not need to worry about the changes.
Comment Changes
The 20 second comment restriction is being removed. Currently, when you make a comment you have to wait 20 seconds before you can leave another. This becomes particularly painful when trying to reply to many people on a post. In HF20, users will be able to make a comment per block just like you can with voting. Posts are still restricted to once per 5 minutes.
Increase Account Voting Power Precision
For accounts with enough SP to cast sub 1% votes, their VP was being wasted due to a rounding issue that HF20 has resolved. Due to the increased precision, accounts will now be able to vote sub 1% weights without losing out on a disproportionate amount of VP. This should help with large accounts that have to perform a lot of small votes for content moderation or curation.
Upvote Lockout Period
One of the more complicated changes for average users will be the change to the upvote lockout period. Currently a user is not able to upvote any post that is within 12 hours of paying out. However, users can still cast downvotes during this period of time. In some rare situations, this led to abuse where users would issue downvotes that could not be countered no matter the desire of the network. With HF20, users will now be able to upvote OR downvote a post all the way until it is time to payout. However, in the final 12 hour window, upvotes and downvotes will lose their power linearly until 0% at payout time. This will allow posts to receive votes for longer, hopefully allowing them to receive more exposure as well as prevent uncounterable downvote abuse.
Beneficiaries Payouts
Currently, if you set beneficiaries on a post, the reward will be paid out 100% in SP regardless of the post reward options. In HF20, beneficiaries can now also be paid in SBD if the post is set to 50% SBD/50% SP. This should increase SBD supply and help keep SBD closer to its $1 peg.
SBD Print Rate
The SBD print rate change has been extended from starting at 2% debt ratio and ending at 5% debt ratio to starting at 9% and ending at 10%. Some of you may have noticed that, at times, your posts payout with some SP,SBD, AND STEEM. This happens because of the debt ratio from the amount of SBD on the market and its price relation to STEEM. The change in the debt ratio hopes to help keep SBD closer to its $1 peg.
Testnet
The changes detailed for HF20 will be deployed to a testnet on, or before, August 25th, 2018. This will give users and witnesses enough time to test the changes and delay the release if necessary. After a period of testing, the final release will be tagged and become active when 17/21 witnesses have updated their servers and started signing blocks.
Questions, Comments -- Get In Touch
Due to the immense amount of changes in HF20, this post inevitably grew a bit longer than planned. As the goal here is to help Steemians understand the changes planned with HF20, I would like to invite anyone that wishes to join the SteemDevs Discord Server - channel #hf20. There is a lot to discuss and even more to look forward to in the coming months.
Links
Vote @netuoso as Witness
- Click the link above and input your active private key when asked to vote
- Alternatively, visit https://steemit.com/~witnesses
- Or click here to set @netuoso as your voting proxy