This thread makes an important point that's largely overlooked. Much of the "reduced severity" of Omicron comes from a change in the mix of people infected, with Omicron hitting a larger share of vaxxed/previously infected, while Delta is hitting mostly naive subjects.
If Omicron is, say, 70% as severe for an unvaxxed, uninfected person, it might generate only 30% as many hospitalizations for the population as a whole, because the vaxxed or previously infected are unlikely to go to the hospital for any strain.
https://twitter.com/_nickdavies/status/1473941671196905478?s=20
If you're unvaxxed/uninfected, Omicron is probably slightly less severe but more contagious. If you're vaxxed, it's probably slightly less severe, but Delta wasn't too bad either - but your odds of getting infected are much higher.
While January looks to be awful for US hospitals, there's another reason for hope.
South Africa's apparent peak was real, and it's possible that London may be peaking. (UK as a whole still going up.) If that holds, it's unexpected, and I'm not sure what the cause is. But it would mean that the total number infected by Omicron may be 1/2 of some previous waves, but packed into an incredibly short window that can slam the hospitals.
Again, too early to draw firm conclusions, but let's hope for the best case - lower severity and a fast end to the wave.