I think there's merit within different ranges to produce a mini-series or two, eg in WWII there were German cavalry (GC) and Fallschirmjager (FJ) ranges, which no-one expected to fill into a giant DD or WS series but which were still collectible in their own right as the sets within each range bore a good internal cohesion, eg you could put all 7 GC together and one wouldn't be galloping away from the others. That aspect has been lost to a certain extent within the enormous ranges under current production, and the lack of consistency, eg kubelwagen in FoB to draw in collectors to that series, Winter Germans in the WS range instead of WS(W) or BBG, and so forth.
Personally I'd be happy to see a return to some American history themes previously explored, ie Rough Riders (RR), Vietnam (VN), the West (TW), and perhaps some more Ancients eg Greek -v- Persians (Thermopylae or Marathon or Alexander the Great), perhaps a few mini-series to compliment the existing ranges (ie a Napoleonic 'Eastern Front' theme on the retreat from Russia, or a 'Battle of Leipzig' to cover the French/Polish/Saxon -v- Austrian/Prussian/Russian/Swedish forces).
However, I can appreciate the time and effort it takes to plan and execute a series, and I'm quite conscious of the fact that quite a few themes which should be overwhelmingly popular (eg Fall of Rome/Barbarians) haven't hit the heights expected (but the linkage to the Ancient Egypt offers another dimension to both the Roman and Egyptian series).
More please, and retire the LAH please!