It's actually a bit difficult to come up with "good" future destinations for BA from Heathrow, as pretty much all the worthwhile ones have been done.
Regarding the old "BA from the provinces" proposals, those times have been and gone. When you look at the other European operators they likewise have hunkered down to just one, or for a few, two, hubs, and that's it. Legacy operators have just become hub operators. BA have a sizeable operation from different London airports to Nice, Air France don't even bother with the route, although they have substantial operations to Paris at both London and Nice. But spoke-to-spoke flights just seem destined to be left to the LCCs.