I think it poses a big question --- whether Bitcoin will remain due to it's advantage of being the first or will it be dethroned by others. Fact is that decentralization is the future. Everything that can be decentralized will be decentralized. Ripple is perhaps the last pathetic breath of the centralized money transmitting system that is based on debt (IOUs).
I think the advantage is the key point and bet on the advantage.
But even Bitcoin used for real transactions is of course based on IOU. Any money is and always will be. Otherwise it is not money.
Bitcoins have nothing to do with IOU's because there is no debt system inside Bitcoin plain and simple.