I just don't see how a Sega comeback should end well. The market has changed when Sony and MS entered the market, with their giant budgets. Remember, last gen almost broke Nintendo's neck.
Next problem: Traditionally Sega's audience is almost identical to the Sony/MS audience. But there's absolutely NO point in directly competiting against PS and Xbox with a conventional console. It's suicide (that's why Nintendo had to gamble with the Wii - and won). They would need a USP, some big feature to completely differentiate their system from all others.
Next problem: Their own IPs. Take their mascot from better days, Sonic... he is absolutely deranged. The rest isn't strong enough to drive a console's sales, even as exclusives.
http://vgchartz.com/worldtotals.php?name=&console=&publisher=288&genre=&minSales=0&results=50&sort=Total
Currently playing: NSMB (Wii)
