The Terran Sea frigate fleet, the follow on to the Isometric, ended up being completed in 3 separate classes as technology advanced. The original Terran Sea A has already been bought up to B standard but now the DDS are looking into bringing all Bs and older Cs into the final C2 standard.
To get up to C standard Bs will need a new engine core and a new databus able to take the demands of FIDO 1.0 VR crewing. Sensors will also need to be upgraded and all ships not C2 would get 360 CIWS (some ships in both classes already have this). It would be costly but would result in a standardised fleet of 21 very capable frigates. The standardisation would reap cost benefits in years to come too.
