You know, Sega better not be bankrolling on their die-hard fanbase. I'm still irritated from them pulling the DC with so little fanfare, shortly after pulling the Saturn and 32X (both of which were obstensively junk, but hey).
Besides, axelblazeadam is right. There are already 3 very well established consoles. Sega has been out of the marketplace for a very long time and their name doesn't have as much of a value as it once did (its zenith, arguably, during the 16-bit era).
There is a positive for it, I suppose, and that is all the Sega titles would be on the sega system. However, don't forget that since the DC lacked third party support, Sega was stretched to the limit to meet the demands of all the genres on its own. We all saw how that failed.
If Sega were to come out with another console, we would definetely see companies working even harder to lock up third party developers. MS, most certainly would work harder. The 2nd spot is theirs to lose, since Nintendo isn't the force it once was.
I know there are other people on this board who have been clamoring for a Sega system (with good cause, I know), but I'm not one of them. So I'll be the cynic, and take this with a grain of salt.