Pretty much what Ohtar said. The ideal WOTC official release, to me -- ideal modulo realism, that is -- would consist of one HC combining MOTP/PlH/ELH to act as the official sourcebook of Planescape; one PS Monster Manual (combining, and hopefully restatting, all the previous monstrous releases + new unconverted planar beasties); and one HC compendium of the "classic" modules of Planescape, similar to Paranoia Flashbacks, updated for 3.5.
[Stuff beyond that would be awesome, too, I suppose, but there'd be no way in heck for it to ever happen.]
I'd be game, if it was as good as the original (not necessarily the exact same; things would change some, after all...)
If Wizards were to give it a shot, I'd prefer they at least consulted the people doing the releases on this site- I think they've done a very good job maintaining a lot of good aspects of PS.