Lots of enthusiasts don't seem to like it, but the future is light weight, engine under the floor, high power to weight ratio trains, not ones with huge power cars at each end like the 373s able to draw ~12Mw of power when accelerating in a section of tunnel. Efficiency will be key I believe, as the UK National Grid in the south east is not strong enough to have HS2 running lots and lots of 12Mw trains off a single phase input, especially if you need tunnels out of London, so you will need to use phase balancers as is the case for HS1. That is another great reason for using more efficient modern trains as a starting point than using 373s.
It's not just enthusiasts. The customers have spoken on this issue elsewhere too.
373 do have a maximum continuous rating of 12.2MW, but it is possible they'll have short-term peaks of more. However even if you distribute the traction systems along a train, it'll still be around 10-14MW - whether it's distributed or concentrated, won't make much difference to the load on the national grid.
I wouldn't suggest using them on HS2 though, but it would be useful to have trains that can be run beyond HS2. TGV's aren't "hostage" on LGV's - almost all of them venture beyond the high speed lines - of course they don't have the loading gauge restrictions there that we do, but to have a flexible system and avoid changing trains (which passengers don't like - especially if they end up paying a premium for the high speed portion of their journey) then it would be beneficial to have a through train system. In which case you'd be better off packaging the proven technology you refer to (TGV/ICE) in an envelope that fits on our classic lines.
This has already been done... class 373. So while people are mentioning it - I think the best way to put it, is a next-gen 373 (whether with distributed power or power cars) would be a good place to start for the longer distance services.
