I'm not running 3.5 right now but I'm designing new campaign material with it and hope to be running a new game soon, probably online. I never switched to PF; I didn't see the point. "If you like 3.5, play this instead," doesn't really compute for me, although I've read a lot of PF and think it is very good.
I like 5e enough that I'll happily play it or DM it but it hasn't convinced me to make it my primary system, so this is great news. I'll be picking up this and the other core books when they come out.