The major differences between the 2E --> 3E switch and this one is what causes the most concern for me.
#1: 2E was broken. New rules were constantly introduced in 2E to top the previous supplement. 3.5 hasn't come close to the powerups that occured in 2e (kits anyone?)
#2: We have had only 4 years of version 3.5. That's it! Only 7 years of 3.x up to now. We had 11 years of 2E (9 when the announcement came).
#3 (and the biggest one for me): Adventures.
Thanks to WotC and 3rd party publishers, especially Paizo, Necromancer Games, and Goodman Games, we have literally hundreds of adventures. I want to run many of them, and I don't intend to convert them to a new edition before I do so.
#4: Class Options. There are so many class options for 3.5 that I haven't even gotten to try yet that I feel like I've bought something (actually many somethings) I'll never use (if I go 4e).
So what I have decided to do is this. I'll buy the three 4e core books. I'll port the ideas I like from 4e into my 3.5 game and leave it at that. I will not join the D&D Insider (though I will certainly use it while it's free).
And I'll take a break! This will give me a chance to catch up on the 3.5 third party products I don't have yet, and then just save some money.
I'll start collecting books again when 5e comes out - if the hobby is still alive then.