I think that no matter the success of Next, there will be people on ENworld that will claim it is a failure. An the opposite.
With that said, I voted success, because (based on the playtest) it looks like Next will be an edition that my players and I will enjoy playing. So whether it will last 3 or 10 years or outsell Pathfinder or not is not really important. Support is great, but as long as I get a core system that I can use, all is good. I mean, we recently broke out our 2e books and had one of the best campaigns we have had since the 90's.