Intuitively, the popularisation of FaaS feels inevitable as lower level technical challenges get solved and give way to abstractions like this. Who knows though what our stack will look like in 20 years.
Although with FaaS, I don't see anything particularly new from a development perspective. It's, well, functions. Most of the time they aren't communicating in any kind of novel way, and often they're doing the decade-old stuff of reading files and slurping databases. The abstraction being more on the operational side of things this time.
Not that I'm complaining or doing the "it's just CGI" dance. Compared to other "cloudy" tech, there's actually potential for simplifying things and not just simulated VAX computers with more effort…
But any abstraction runs the risk of revealing itself as a leaky abstraction, not worth the overhead. That's been my experience with functions.