I will end up buying at least some of the Essentials material, but my gaming group will almost certainly not move back to 4e. We tried and failed to be passionate about 4e and decided not to move back to 3.5, and for the last 7 months have been making a system we enjoy from scratch, and it will go on.
Echoing several others, if Essentials had been the original form of 4e it might not have happened this way. For me, the single most disappointing thing about 4e was the identical (and in my opinion thematically troublesome) at-will/encounter/daily progression and the explosion of sometimes barely differentiated powers it entailed. Playing with that was almost instantly the focus of my mechanical tinkering. Otherwise, I found a lot to like about 4e. With Essentials I applaud Wizards for branching out more radically than I expected without sacrificing the interoperability of the game, so far as I can tell from the previews (YMMV). In a year I think there will not be much residual furor, and enough people enjoying the game with Essentials classes that even those existing 4e players who didn't prefer its design direction will accept it as basically good for the game. All it takes is one good gaming friend falling in love with one of the new builds, just enjoying the heck out of it right at your table.