I would rather them buy Mystwalker so that they can make a fukkin sequel to Lost Odyssey.
Microsoft and Sega partnership predates the Dreamcast, not just that, Microsoft been wanting Sega for ages and seeing how they turned themselves around after their downward spiral, plus owning Atlus. That alone would fukk up the industry if they get Sega, but in return, Nintendo and Sony loses out big time on not having games like Shin Megami Tensei and Yakuza on their platforms.
Also, Sonic the Criphog always turn a profit so that's easy money, Phantasy Star might gain a resurgence in the west and with their old ips, you pretty much become a behemoth.
Why didn't they buy Sega after the Dreamcast folded?