If Mint disappeared, I think I'd go with Debian and CrunchBang (which are the two other distros I'm using right now). I'd also take a look at Arch (and arch-based distros like manjaro).
This topic was started on June 24th 2010, so I think "tomorrow" has passed us well by Let's celebrate instead that Linux Mint is here, stronger than ever, 2.5 years later!