I admit that the concept of retrieval miners makes no sense to me since it seems like they would have to be the same as the storage miners. It is worrying that the whitepaper says "we must assume that there is always one honest Retrieval Miner"; you can't assume honesty without incentives.

In general, I don't take the Filecoin whitepaper too literally. There are a lot of aspects of it that will probably have to be changed. I think the Filecoin ICO (which I didn't participate in BTW) is more of a vote of confidence on the team, not any specific protocol.