5e could hit Paizo hard. Really hard. The company has been growing at a steady pace buoyed by heavy sales. If WotC starts taking back sales that might lead to belt tightening at Paizo as they have to trim staff they can no longer support. But I don't think they're in danger of going under any more.
Your right it could, but what I've found out by talking with a lot of my fellow society players, people play Pathfinder for Pathfinder. You aren't going to find Pathfinder in Next, in 4th edition, and even in 3rd edition. If I want a game of Pathfinder, or even 3rd edition, I am going to play those particular games. I'm not going to buy a game like Next and attempt to morph it into a likeness of either of those two games. That is one of the main reasons I think Next is going to fail because instead of playing a game that attempts to mimic certain editions, you can just go and actually play the edition you are trying to mimic.
I also look at Pathfinder and Paizo as giving you the equipment to play a game of baseball (the rules), while at the same time, giving you plenty of field (the AP's and modules) to play the game on. Basically all you have to do is bring your own players and they provide the rest.