MS could probably land a deal to get MGS 6 exclusive, but it wouldn't help MS all that much. Metal Gear series has always sold more on PS, maybe a 1/4 of the sales were on Xbox. MGS V is at about 0.5 to 1 million on Xbox vs. 2.5 to 3.5 million on PS. Just wouldn't make much sense to get it exclusive. I think the Tomb Raider deal with Square Enix will probably be the last one MS does. MS seems to be more focused on new ip for Microsoft Studios (Quantum Break, ReCore, Scalebound, Gigantic, Sea of Thieves, Cuphead, Below..etc.) and existing franchises (Crackdown 3, Gears of War 4, Halo Wars 2, Fable Legends..etc.).
Besides MS already has a deal with a renowed Japanese game developer, Keiji Inafune and comcept. Maybe he's not as well known as Kojima, but a legend nonetheless. He did create Mega Man and Dead Rising.
