JJK should still be going.
We should be 400 chapters in on some kino, lore exploring shit, or on the other side of it in the final big arc.
The original series practically DEMANDED a long ass Heian period arc. Hell, Gege could have made it a bridging series in between a Part I and Part II of JJK, like an extended version of Kakashi Gaiden.
This could've gone a million different ways, but we should have learned more about the clans and their origins. We should have learned about Heian Period, Sukuna, Tengen, Kenjaku, Convergence, Six Eyes, Michizane Sugawara, Vengeful Spirits, and so much more.
Gege set fire to billions along with his own legacy as far as I'm concerned. Jumping ahead decades and adding fucking aliens, get the fuck outta here with that bullshit.
I don't doubt the numbers for Modulo are at least acceptable, but how much of that has to do with anticipation for characters, revelations and resolutions tied to the original?