Hell yeah. I believe that if Spelljammer is done, it'll work like a "D&D Star Trek" where space exploration is the prime focus, rather than using it as a highway between Toril and Krynn.
I agree, it needs to work as its own setting. I don't object to it linking other campaign worlds, but that doesn't really take advantage of what SJ has to offer, IMO. DMs can already link campaign worlds if they want to.
And D&D Star Trek sounds like a pretty good kernel to start from. (Funny thing about SJ, it kinda steals back what Star Trek/sci-fi stole from the fiction surrounding the age of exploration. "Sail to strange, exotic lands, fight their men and, er, romance their women.")
Just spitballing, but if Wizards go with the space exploration angle, a couple ideas:
1. Really robust planet/whatever & critter creation rules. Space is big.
2. Module-as-planet.
3. Lots of quick write-ups in PDF form on the Wizards' site.
4. A series of unique and adventure-lovin' worlds in greater detail than the modules and quickie PDFs.