Death. Any Muslim who converts in a Muslim country is at considerable risk of death. If a Muslim converts in a western country, their friends and family are likely to kill them, but it can be possible to get away with it if other Muslims don't know about it.
But if a prominent Muslim offends in this way, a fatwah will be issued against him, as was done with Salman Rushdie. And who could be more prominent in his supposed "conversion" than Barack Hussein Obama? They can't necessarily kill him, because he's surrounded by Secret Service agents and police, but they would certainly threaten to do so.
So the question arises, why hasn't a fatwah been issued against him? Why aren't his family disowning him? I think the answer is becoming clearer and clearer as the facts emerge.