I'm with @
Retro Grouch on this one. I usually buy components for the bike i have now, not for an as-yet unspecified bike I'll get some time in the future.
MTB's have gotten so specialized and mission-specific, that it'd be impossible to future-proof a wheelset for a frame you haven't decided you want yet.
Besides, short of a really heavy, high-speed crash, my frames tend to outlive their original wheelsets, so i'm more likely to have a frame with no wheels, than wheels with no frame.