In my opinion, D-Commerce will be a thing when the Bitcoin Lightning Network evolves.

Because for this you need a network with the most security. At the moment it is Bitcoin and I dont think that a POS can beat that. If POS will get ultimately secure we have the fact, that most of values concentrates on a few people/entities. Look how money is distributed. But with POS these people would get to much power. Change the rules, censored etc. Look what happens with steem.
But that does not mean that there will be a solution for this.

Ok so let's go on with at the moment the biggest network. Now it would be just stupid to buy things with BTC because of the fees and volatility. The problem with the fees would be solved with Lightning and the volatility will be solved over time I think. Right now it is that volatile because it is relatively new and relatively small, so big players still can disrupt it with big money. Imagine a merchant would accept BTC payments. Next day BTC price drops hard and he could not fill up its stocks again because his supplier only accepts FIAT. Too high risk. What you already said it has to become a closed loop, to solve this.

I'm at a point where my eyes are focused on the lightning network or another 2nd layer solution. This could get a game changer. Look at "Strike" from Jack Mallers. Mind blowing.

Ok I just wrote some thoughts down. Sorry that they are not in a nice order or what not.

But in conclusion and only my opinion:

We need the safest network for storing our value. More practical use cases and the scalability will be achieved through 2nd, 3rd etc. Layers. (ETH, ADA etc. Could be 2nd layer solutions of bitcoin as well)
And we need apps, software etc. that make all the work and is easy and intuitive to use. You want to send funds to someone? No problem, the app will automatically choose the right network to send it with the lowest possible cost.

It's still a long way to go, but it is a interesting one and with a lit of opportunities.

Just my 2 satoshis.