I think all of the bands mentioned in this thread will hold up, but not necessarily achieve lifelong legend status like the Beatles, Beach Boys, Zep, etc.
I think Nirvana and Pearl Jam will achieve that status to the masses. The other bands like AiC, Soundgarden, Sublime, STP will always be in demand, too.
Jane's is probably my favorite band from that era. In 20 years, I think Jane's fans will still be listening, but I don't think they'll be at top of mind for most when this kind of discussion takes place.