It's fairly standard. With unmitigated spread and the lack of immunity in the population, pretty much everyone would get it. Asymptomatic spreaders makes it worse. It doubles every 5 days or so without precautions in place, so 1 infection leads to 1000 within 7 weeks, which leads to 1000000 in 14 weeks.
Cali is already at 25,000 diagnosed cases (so probably 100k to 500k people infected). In a month that would be up in the range of 3-10 million if people went back to normal.
People keep citing Sweden as a model. Sweden is still social distancing. They shut down any large gatherings and sporting events. You can eat at a restaurant but not at the bar. I think high schools and colleges are closed. So I think that's what it will look like when we start reopening.