I think the first non-Christian president we have will probably be a reformed Jew, or maybe even an Atheist. There is no way that a Muslim or practicer of an Eastern Religion would ever get elected in this counrty.
To be fair, we already have Muslim and Buddhist Congresspeople. And Obama is of partial Muslim origin. I honestly think we will be ready for a Muslim or Buddhist President by the end of this century, or possible even by the middle of this century. That doesn't mean one is necessarily going to be elected that soon. Just that we will be ready to elect one if the right candidate appears.
But you do have to admit that the American people whould take a Jew over a Muslim or a Hindu any day.