Fully agree. To develop on your point, frigates start resembling destroyers more and more. When a frigate has AEGIS-type radars, can launch 30-km range AAW missiles and is fitted for but not with 120-km range AAW missiles (the Aster-30), and BTW the ship is 140 metres and 6000 ton, you could start calling this a destroyer...
So once you have 2 dozen mega-FFGs/DDGs, frankly this does the job even for a Navy like the RN which still has business all around the world.
The key point however, as you mention, is that the new FFG programme had better start fast and provide ships close to T45 size & weaponry. A programme already existed to replace the T22s but it was stopped for budget reasons last year.
The UK's MOD should start looking closely at FREMM, adapt it to RN needs and start building it without wasting years on R&D ...
cheers