I think I know what the OP means and I’d do the timeline kinda like this:
1974: Jaws becomes the first summer blockbuster. It doesn’t even have all that much action or special effects.
1977: Star Wars shows what is possible in a scifi action movie.Before Star Wars, scifi movies were incredibly cheesy looking. Star Wars’ story was just as cheesy but the use of practical effects made it look amazing. I just watched it recently and it still looks pretty darn good!
1980s: rise of the action stars. Five or six bigtime action movies a year, plus countless direct to video cheap action flicks.
1991: Terminator 2 changes the game with the first serious use of CGI effects. But the T-1000 doesn’t have to look realistic, it just has to look cool. CGI is still not being used in place of models.
1993: Jurassic Park changes everything, with CGI rendered dinosaurs that look better than any dinosaurs ever put to screen. The CGI revolution in filmmaking is officially underway.
1990s: the remainder of the 90s features mostly the 80s approach to action films, with a few disaster films and scifi films really pushing the limits of CGI but most action films using it sparingly.
2000s: This is when big budget films with loads of explosions, CGI, and constantly pushing the envelope of just how massive you can make an action set piece really starts to accelerate. By this time we’re seeing perhaps a 5 or 6 big budget movies of this type and a dozen smaller budget films. The Matrix movies are probably the biggest influence during this period, as well as the Star Wars prequels.
2010s: With the superhero craze things accelerate even more, with about a dozen big budget movies each year from 2009-2012, getting closer to 15 between 2013-2016 and looking at as many as two dozen in 2017 and 2018. Marvel obviously has been pushing the envelope there. And by this time it’s not just CGI big budget action/scifi films, those computer animated films are hellaciously expensive and also coming out at a faster pace. Pixar used to own that niche, then Dreamworks established itself, and now you’ve also got Illumination(Minions), and Focus Features(more artsy, but still big budget releases like Kubo and the Two Strings). Oh, and can’t forget Disney.
Is there a bubble? IMO, yes and no. Audiences aren’t going to get tired of these movies like they did with spaghetti westerns. Movie genres don’t generally go out of style unless quality dips to the point where it all just becomes so ridiculous that it becomes a punchline(slasher films in the 80s, spaghetti westerns in the 70s). As long as superhero movies are good, people will pay to see them.
But where there is a bubble is that we’re reaching the maximum number of blockbusters. In 2017, from about March to August there’s a big budget film opening nearly every week. You can’t really have more than that, but in 2018 they might actually have to open two or more big budget films in the same week and have them go head to head. Some companies are going to lose a huge amount of money.