This is an interesting topic but something that will be difficult for the airlines logistically.
I actually like Club Europe and its offering. The lounges are great and I think the seating and personal space on the aircraft is reasonable- 34″ pitch is decent. Catering seems to have improved slightly. However, some of the seats are really battered, and it is odd boarding a brand new factory fresh A319 and then sitting on seats no doubt used before on the 757 fleet!
But this is not a discussion about the BA product, but all European products, and for a 3 hour plus flight, this kind of seating is not so attractive. Arguably fixed seating is already coming in, BB mentioned BA and Moscow, well Turkish have their long haul product on some LHR & CDG flights, but the 737-800 I was on last year had 2 x 2 big seats (but not lie-flat) on a IST-LHR flight.
The benefit of the current products around Europe is flexibility. I suspect this will stay, except for specific routes where there is loads of demand for a premium product, and a predictable number of PAX.
AF I flew C a short while back within Europe, which was decent (although catering rather poor) but would I really want this product on a Levant or Yerevan route? Not really. A few years ago I flew ATH-LHR on a BA767 in a CE seat – very numb bum by the end of that.
I think 3 hours or more is where a superior product is needed.