I think the X1 will win this year and the gen in the US. The only way Xbox One beats PS4 is by selling at a better price, and luckily MS can make that happen.
I would expect PS4 sales to remain strong though. It is a fantastic achievement that they have managed to make the US competitive again after last gen, and Sony really have no reason to get into a price war when they can continue to sell well and make profit. MS's actions in the US are very telling, and Sony does not need to do the same.