Last year, D23 was actually the weekend before SDCC, and they did both. At D23 they featured Infinity Wars, SDCC had Black Panther and Thor. Next year D23 will be a month after SDCC; I expect Marvel Studios will have panels at both for Phase 4. Feige has said multiple times that if you can't overdeliver at SDCC it's not worth doing, so their presence in Hall H really does seem to depend on their production schedule.
I’m guessing with the shareholders approving the Disney/Fox merge we’ll see what Feige has planned for the expanded MCU, which I’ve heard is a 20 year plan. And am leaning more and more on their absence this year was because the merger wasn’t set in stone. And there was no telling how long it would take. The property rights will still take a while even after the merge is completed. Plus Fox has some movies already slated for release next year.
Would love to see Galactus as the next big bad! And maybe a reboot for xmen and fantastic4.
I suspect this year’s calm Hall H was a lucky year and likely won’t be the case next year. Not necessarily bad for me because it frees space on the exhibit floor and smaller panels. Lol