You are mistaken, these aren't fads but buzzwords. Web 2.0 is the web of API, NoSQL existed well before the term was invented and microservices are a valid software architecture since it's not a question of size but an organizational concern. Even "severless" is just the good old worker queue system. And yes, buzzwords come and go but nothing behind these are fads.
My great idea is to make a blockchain version of HN and instead of karma you get HNCoin, just need a 100 million dollars and a top-100 userbase...