It would totally make sense for the only returning characters to be Simon and Doric. I think it would be cool to see them with a new party after a short timeskip between movies. Both would make great leads after a little off-screen character growth, and Edgin and Holga don't really have a reason to adventure anymore.

The new actors (or original actors playing different characters?) could explore other PC classes we don't see in the first movie. We'd get to see some more magic. It would be great