I'm not speaking from experience or inside knowledge, but I'm making an educated guess that consistency in number of F seats is NOT a requirement for Star Alliance. In fact, the number of cabins isn't even consistent amongst airlines. If you think of each airline's individual onboard (and ground) product, they vary from airline to airline in both Star Alliance and oneWorld. Even in one market alone, one carrier's Business Class product isn't equal to another.
Looking at Star Alliance only, here are some facts to support my remark:
TRANSATLANTIC
-British Midland has Economy, New Economy and Business
-United has Economy, Economy Plus, Business and First
-Lufthansa offers only Business Class and Economy Class on some Transatl flights
-Lufthansa uses the VIP BBJ/A319 (forget which) with one premium class
-SAS has some sort of premium seat in the first row of one of its cabins (can't remember which)
-USAirways has 6 F seats on the A330s still, but are sold as C class.
WORLD
-Singapore Airlines has a flat bed in Business Class - most other Star Alliance carriers don't (I know LH is installing them now on the new Airbuses).
My opinion is that in an ideal world, each airline in a particular alliance would have the same number of classes of service to offer - which would give the customer a seamless and CONSISTENT service/product. I think each airline should offer the same basic amenities across the board if they're going to sell themselves collectively as a seamless travel experience. Some of the carriers have a Premium Economy product, others do not. Some have flat beds in Business, others have standard domestic F seats. Some have seatback IFE, etc. And so on... the list goes on.
Who's in agreement with my opinion in favor of consistent products and services amongst all alliance carriers?
-L1011flyguy in Miami