The CDC has been all over the place on estimating the prevalence of omicron. Last week it pegged the number at +90% but now it's revised that to around 50%.
Given trends elsewhere and the high incidence of US covid before omicron, I suspect it's the lower number, which leaves plenty of runway for cases. I wouldn't be surprised if they double from here but that assumes enough testing capacity. In New York City, where it's currently hitting hardest, testing is maxed out.
Ultimately, I don't think this wave matters for markets. We can see that clearly in record daily highs. I think the market can easily handle 500K cases per day, but 1 million? That would be a bit frightening. In any case, I think we can safely assume we'll be seeing record daily cases hitting for awhile in the US and many other countries.