Artists are eligible for the Rock and Roll Hall of Fame 25 years after the release of their first album or single, meaning Nirvana are eligible next year because their single "Love Buzz" first appeared in 1988. However, not many bands get in on their first ballot; Metallica even had to wait a year.
Still, while nothing is certain, it seems quite likely that Nirvana are first-balloters. Who should induct them? Michael Stipe? Eddie Vedder? Neil Young? Patti Smith? Beyond that, will Dave Grohl and Krist Novoselic perform a Nirvana song with a guest singer? Will Bleach drummer Chad Channing get inducted, too? Hopefully we'll get the answers to all these questions next year.