The 4090 isn’t that much better than the 4080, and the 4080 is much more energy efficient. I guess it all depends on what you consider “blowing previous gens out of the water” but that’s sort of marketing non-sense.
If you have a 3090Ti you aren’t going to be missing out anything on current gen games, and current gen developers aren’t in a hurry to develop exclusively for hardware most of their potential consumers aren’t going to be running on. So basically, it’s just “blowing previous gens out of the water” on flair at the moment.