IMHE, FwBs are transient relationships that may promise a bit more than they actually deliver.
Two dudes who find each other both sexually attractive and otherwise compatible go for a relationship of some kind. If at least, one of them is unavailable for any reason, they tend to go for the FwBs mode. It is a bit like neither fish, nor flesh, nor good red herring thing. So, I would not raise my hopes too high.
I met a guy at one of the professional conventions I was attending, and we clicked right away. He was not out, and was determined NOT to live as a gay man. He wanted a family, kids, white picket fence, etc.
It turned out that both of us were working for a major corporation as free lancers. This involved lots of travel, hotels, dinners and the usual corporate socializing all over the continent.
It turned out that he was a sex-starved bottom dude. I found him pretty attractive, so besides sharing a very similar line or work, we also had the sexual bit which worked out pretty well.
The dude was pretty high-strung though, and neither he nor I saw each other as regular BF material. (He was determined NOT to have a BF. And I was not interested to go to that length with him.) But we had quite something to talk about. We usually stayed at the same hotels, and mostly traveled for work.
It turned out that both he and I figured quickly out that trying to hook up in yet another town we landed at with the dudes we did not know was going to involve some footwork. You also had to work the next morning. It only made sense to hit the hay after the dinner, do the deed, take a shower, and repeat it all in the morning before getting down to the grind.
It all worked out just fine for as long as he did not find a more down-to-earth, Mo-Fri, 9-5 job that was going to help him start a family, etc. So, he virtually dropped from the radar. No regrets, though.