To expect anyone else other than Doctors, for while at least, is just incorrect thinking. I am ever the optimist when it comes to BCS, but even I saw the emphasis when they said '...lesson learned' when it comes to ancillary figures like Rory or even River.
Time moves on, people move on and so does the show. When the Amy figure was finally ready to move, Karen Gillan had already been off the show for a year. Potentially, the 'Amy Scenario' could be just as true of Jemma-Louise. Pixie is right in saying that BCS needs a string of sure fire hits as its next series of releases or (and this by their own recognition) they would be in real trouble.
Doctors all the way for a good while then I think. We have David Tennant's Doctor that sold out on PO, Tom's is ready for PO (this week we have been told...though it works better for me next week fellas!) and plans for the #1 Hartnell are underway so that all sounds just about right.