Competition is incoming, so it smells like the incumbents are rushing to close the manufacturers' doors from the competition by mass ordering, and it's good PR to quote a London service.
Half of those London services won't ever see the light of day until serious station work is done at St Pancras and Gare du Nord anyways.
You also have Gemini, Claret, Illisto (Kevin Speed), that will be on the market (assuming they really have intentions to do so) in the near future for stock. If everyone orders at the same time, the new entrants will be in a proper pain situation
I have been doing a bit of internet sleuthing, but having to use google translate from French, so some accuracy might have been lost.
As far as I can work out TrenItalia have now confirmed their train order (basically a common fleet of Hitachi Frecciarossa 1000 with their French Operations). That puts them ahead of Virgin who have a letter of Intent with Alstom for 12 Avelia Stream (but I can't find anything saying order has since been confirmed).
Also most of the articles I looked at for TrenItalia simply refer to London (or Londres because they were French), doesn't actually say the station. However at least one article seemed to mention Stratford International.
I might be going off at a tangent, but I wonder what the relative costs of staffing Stratford International are, compared to cost of paying fees to use St Pancras International. Assuming trains reverse at Camden spur and are serviced at the new Paris depot, do they even need to serve St Pancras. I guess it is a rail equivalent of not serving Heathrow, but instead accepting an alternative airport.
At the moment, details are so vague, that can't really say what is planned, or what tricks they might have up their sleeve, although not announcing stops competition planning so is commercially clever. Although whilst St Pancras isn't confirmed I don't think can rule out terminating at another UK station, and Stratford is effectively London if you are starting from Paris area.