Realistically, what is the biggest franchise that Microsoft can buy out that would give them first place in console sales?

[starcraft]

I do not believe that is possible at this point.

If it is possible, it would be GTA.

It would also be a purely hypothetical scenario, as GTA's value to Microsoft would related purely to Xbox (as opposed to Minecraft which has multiple applications), would cost billions of dollars, and they would not recoup that investment.