The End of The Golden/Silver Age of Manga?

Yeah and to an extent, I think we have a perception that the manga industry was "better" back in "our day" just because we hadn't seen the same overused tropes. They were NEW to us then! Even now, I can struggle sometimes to enjoy newer media just because I've seen "so much" of it already before. Character types, set pieces, arcs, tropes, plot beats, etc. 

Of course, new stuff that uses old tropes can still be fresh, but yeah.

That said, I wouldn't call the manga industry dead yet, especially if you count more independent publications. Sort of like with film, sure, plenty of newer "big blockbusters" don't feel fresh or interesting, only tired out, but indie film is as hot and unique as ever, and you can still find hidden gems any year.