Worth noting that TGV M has ~8MW in a 200m set with shortened power cars. A Class 373 has only ~12.2MW on a 400m set.
The standard formation is different to TGV duplex, on TGV-M the power cars are about 3m shorter, and each trailer is about metre shorter. But there are 9 trailers instead of 8, so overall length remains about 202m.
Its modular design so could have double power cars each end (with inner one not needing a cab) and effectively 9+9 trailers between.
The previous (Euroduplex) version was rated at 9.28MW (12,445 HP) on 25kv, but only 6.8MW (9120HP) on 15kv 16.7hz systems in Germany, Switzerland, Austria etc. On 1500v dc it is only 3.68MW but of course speeds are lower.
So looking likely that 400m version will get something between 12.5 and 16MW