Pre-school class sizes are smaller to start with 14-18 I believe at most schools. So, if 8-10-12 kids are allowed in a class then they could certainly being go half days or 2 days a week.
It would take some structure changes but in a LOT of places kids only go half days or part -time to actual preschool. The rest of the time kids could be in a "after-care" style class room if the school has a space that will accommodate them. Rec-centers or other nearby locations could also be used for care rooms

I would imagine that schools where possible will keep the same level of enrollment because that impacts their funding. but, don't assume that the number of seats offered equals full time in person instruction for every student enrolled. It's definitely possible that hybrid continues, depending on community wide vaccination and infection rates, and guidance on group sized indoors, etc.

We are new to DCPS/ lottery etc so am hoping someone who has more of a pulse into DCPS/ charters might know more- does anyone know if DCPS schools are planning to shrink the number of PK3 classes available to deal with the pandemic and the need to have smaller class sizes? It sounds like from the re-opening threads that class sizes are being reduced- will that result in less availability to accommodate PK classes?