I'm not sure I was around for the 'first' alchemy revamp, so I can't comment on that really...
The alchemy changes have gotten a lot of positive feedback on the Beta Server from the alchemists testing them, so I'm fairly confident that
most of you will enjoy the changes. Obviously, we can't please absolutely everyone with the changes, but we're happy with the outcome so far and can see it giving potions a decent share of the consumable market, right along with food and drink. This is not to say that we won't make any changes based on feedback post-launch, but it should be somewhat of a consolation that a significant number of alchemists have already tested and commented on the changes, and even more so that I'm actually going through and making some additional changes today based on feedback from the Beta Testers.
As far as the potions we introduced not too long ago (HoT/ Heal / Etc)... The potions themselves haven't been changed much, and the recipes for them haven't changed at all, so you shouldn't have to worry about that too much. The Vampiric and Wrackbane potions are still in there, so you won't need to worry about those either, though they likely have new recipes.
As far as the possibility of there being potions that simply won't exist anymore... There are a few potions that have been completely removed, primarily because they seemed particularly useless. So far, we've gotten no complaints of missing potions on the Beta Server, which is a good sign.