The Type 32 as a drone-control frigate

Will a future River-class patrol ship become the Royal Navy's modular mine-countermeasure and drone platform?

Probably not; that fleet role is more likely to be folded into the Type 32 frigate program.

The proposed Type 32 role is to operate mine-countermeasure equipment and other uncrewed assets with the fleet. That would make it a drone-control frigate, distinct from Type 31. Type 26 is assigned anti-submarine warfare and point defence. Type 83 is described as the general air-defence destroyer, approaching cruiser scale.