Eh, people have been going on about the 'Death of The Movie Star' for decades, frequently in terms of the market having less and less blockbusters, but the older I get the less I believe it and the more it seems like raw demographics.
The Baby Boomers had a ton of big name stars - Schwarzenegger, Cruise, Bruce Willis, Harrison Ford (technically Ford is slightly older than Baby Boomers, but also started later) - both as a function of the population growing with them and continued new markets entering the picture, from industrialized Japan to post-Soviet Eastern Europe, etc. But they've been aging out for years, with Ford arguably not even making it out of the 90s (maybe The Fugitive in '93), Schwarzenegger reduced to the box office of End of Days / 6th Day by 2000, Willis doing DVD drek by the mid 2010s, etc. Cruise making it this long is impressive, but he's also a very young boomer, bordering on Gen X.
Gen X had their own stars - Will Smith, DiCaprio, Matt Damon, etc.- but they were limited by a smaller cohort, less possible expansion overseas (China market was a flash in the pan before they went full protectionist), and Hollywood moving to a more multi-cultural acting base that may not have played as well overseas (Will Smith, Vin Diesel, etc.) Let's be blunt, I don't know if any 25 year olds are going to a movie just because Christian Bale is in it, and objectively, a whole lot of these guys are aging out in real time.
Millenials are a weird batch - while you could argue some like Ryan Gosling are in contention for the biggest stars remaining in the world, _a lot_ of them (and other X / Millenial cusps like your Chris Pratts) were tied up in franchise contracts (e.g. all the Marvel Chrises) that limited their ability to be in movies where the franchise didn't come first, as well as appearing in a lot of streaming releases that don't have box office results.
Gen Z - While this group (even Millenial / Z cusps like Tom Holland and Chalamet) are barely starting to age into movie star ranges, their large population cohort already suggest that they'll have a turn around - if their movies go viral.
So to summarize, Boomer actors had a huge population and new markets; Gen X had a much smaller population and limited industry growth; Millenials had a larger population that was split between traditional media and streaming; Z and earlier are too young to tell.
--
As to the director side of the argument, I would heavily disagree, and say even Nolan and Villeneuve don't have the relative star power of a Spielberg in the 80s. _Maybe_ Villeneuve is equivalent to a late 80s / early 90s Scorcese.
