I think they will probably stay done too aside from little one offs, possibly. They all had their own projects, for one thing, and interest in them had been waning for a long time, with "Imitation Of Life" probably the end point of their real popularity. Critics had probably been trying to keep the flame alive on their last two albums (although Accelerate didn't deserve it) and there was definitely a sense of "hang it up, guys" after Around The Sun. So I think the band members agree they were done and that reunions wouldn't really rekindle any kind of "flame."
I also don't know how much future generations will really pick up on their music. Probably not that much, sadly.