Don't really see much point in it.
Yakuza, Valkyria Chronicles and Miku already release on Sony consoles. Multi-plats like Sonic; Aliens; the 'Virtua' games etc. make their way across anyway.
Total War & Football Manager don't work on consoles (just leave them on PC releases with SOE I suppose).
Otherwise, does Sega have much else of value? Would just be un-necessary spending for Sony to secure a couple of franchises as exclusives that they're already getting. Seems a waste.
Where's all this talk of buying Sega come from anyway? Are they being sold? I'll have to get all their games off PSN before they disappear if so!