I'm a very happy 4e player, but I think it's likely that I'll end up playing D&D Next. I'm expecting that the designers are going to build a game that's a lot of fun for me and my friends, and I enjoy playing a game that's actively supported.
Now, if the next edition comes out and I don't find it to be much fun compared to 4e, I'd probably end up sticking with 4e. But I'm pretty confident that the designers are good at their jobs and will make a game that I also find to be lots of fun, so I expect to move on to the new game when it's available.