My take at the M-frigate replacements:
I based the design of H.Heusers ships, as they have a very realistic future feeling to it.
The ship you see is a combination between the F125, FREMM General Purpose variant and LCS-ships.The ships will have much enhanced land-attack and anti-submarine capabilities. This will better suit the frigates in possible future peacekeeping and peacemaking missions. Also important are long maintenance periods. The ship has to be able to operate for up to a year away from her homeport.
Specs:
Displacement: around 7,000 tonnes
Length: around 160 m
Beam: 19 m
Draft: 5.5m
Propulsion: CODGLAG (2x Gas turbines, 2x Electric motors, 4x Diesel generators, 1x bowthruster)
Speed: 22 knots on diesel only, 33 knots max
Range: 4,000 NM (7,400km)
Complement: 90 (standard crew), 150 max
Sensors & decoys
- SHR Satcom
- ESM Surveillance
- Integrated Communication Antenna System (ICAS) (IFF/L16/VHF/UHF Antennas)
- Advanced Phased Array Radar X-band MFR
- TV&IR Surveillance
- Seamaster 400 (SMILE) S-band MFR
- Navigation radar
- Low Frequency Active Passive Sonar (LFAPS)
Electronic warfare & decoys
- TKWA/MASS (Multi Ammunition Softkill System)
- Sabre EW/ECM
Armament
1x 127mm lightweight Otobreda naval gun with guided VULCANO ammunition for land-attack missions (range: more than 100 km (62 mi))
1x 76mm Oto Melara STRALES with both conventional and guided DART ammunition (range 16 km)
2x 30mm Thales Goalkeeper CIWS
4x 12.7mm Hitrole-NT remote controlled machine gun turrets
32cell Mk-41 VLS with a combination of RUM-39C VL-ASROC and RGM-109E Tactical Tomahawk
32cell Mk-48 VLS with RIM-162 Evolved Sea Sparrow Missiles
Boats & helicopters
2x NH90 Nato Frigate Helicopters equipped for SAR/ASW/ASuW
4x Thales Interceptor Autonomous Surface Vessels
2x Fast Raiding Interception and Special Forces Craft (FRISC)
Probably two or four units around 400-500 millions each. Entry of service around 2024. Life expectancy of over 30 years.