I don't know anyone (at all) playing 4e, so for me it's like 3rd edition has just stopped printing new books. I'm not really interested in pathfinder. I finally have a complete set of D&D with the guarantee that no more books will come out.
So I'll continue to run my games in 3.5 and if new players come along who don't know 3.5 then I'll teach them.
Maybe 5e will interest me. I'll get back to you on that one in 10 years.
Besides, if it ever reached the point that I could no longer find people to play 3rd edition, I'd just run GURPS instead. 4e is irrelevant to me.
This is pretty much where I am.
I wish Pathfinder all the best, but I'm seriously not interested in it. I have dozens of books that are enough for me to game for the rest of my life and still not play similar campaigns twice. Pathfinder will probably be a good game, but I don't really need it myself.
Nobody I know in real life plays 4e, only some people I know friend-of-a-friend that I didn't already game with before 4e came out. The gaming groups I know of in meatspace all decided 4e was too unlike what they knew of as D&D and avoided it like the plague. Heck, one was a playtest group (names in the playtest credits and all that) that dropped 4e the moment the playtest was over and went back to 3.5.
Today, at my 4-year-olds birthday party, an old friend of mine I haven't gamed with in years came up to me and said she was running a D&D 3.5 campaign and wanted me in it (she was there because her grandson and my stepson are playmates). Her words about the edition issue? "I hope you don't play that revision, if you did, I'd have to hurt you.", said playfully, she'd looked at 4e on the shelves and had put it back in horror. She started with OD&D in the late 70's, moved on to 1e, and then stayed with it for over 20 years until jumping to 3.5 in '05, and from the looks of it she's going to be playing 3.5 for the rest of her life (barring a 5e or later edition that more closely resembles the 1e/2e/3e design lineage instead of the 4e evolutionary offshoot). I'm planning on playing in this campaign, and this is a woman who like to run multi-year long campaigns. I don't really see a problem with having people to play 3.5 for a number of years, right now I'd have more of a problem getting a 4e game together if I tried.
Could they make a 5e that would bring me back to buying WotC D&D? You bet! However, it would have to be a return to the "feel" of 1e/2e/3.x instead of a continuation of 4e. It would have to feel like it was an advancement or development of that which came before and not just a a release churned out to sell more new numbered PHB's and yearly MM's.
I hold next to zero interest in playing a 4e campaign, and I would be far more likely to haul out my New World of Darkness, or d20 Modern, or Star Wars (d6 or Saga), or even LUG Star Trek before I played 4e if nobody played 3.5 D&D anymore. If I wanted a game for one of those I could also put a group together for NWoD and Star Wars on pretty short notice.
My hope for Pathfinder is that it keeps people playing in the 3.x sphere of gaming and helps keep newer gamers within the 3.x world, and that the final game as released is close enough to 3.5 to cause minimal issues with people going between the games. I haven't kept up with developments, but as I understand it that is one of the design goals of the game.