You missed a few threats:
User adoption falls off as new users realize probability of reward very little without powering up for a significant investment (4 to 5 figures).
User attrition accelerates as Steemians who have been here 2-3 months see their rewards dried up.
HF20 doesn't address the self-voting problem, where all accounts of medium to whale level SP are incentivized to click on their own posts, or their own circle of friends, and the average user needs incredible luck to see any rewards.
Whales start powering down and crashes the price (you had price crash in there but didn't mention how)
Copyright infringement risks causes Steemit to have to devote excessive resources to edit posts / deal with takedown notices
Copyright infrignment liability if sued by major publisher will create a lot of uncertainty and doubt in Steemit's future. For exampe, see https://steemit.com/steemit/@tommymindtrick/the-steemit-sandbox-puts-us-all-at-risk-due-to-ewhoring
RE: How Will Steem and Steemit Perform In The Coming 12 Months? A Simple Community SWOT Analysis of Steemit!