x00 - Paris (Non-Stop) - Every hour
x15 - Paris (Stratford, Ebbsfleet and Ashford) - Alternate house.
x33 - Brussels / Amsterdam Every hour.
The problem with services calling at Stratford, Ebbsfleet and Ashford is that all 3 locations are going to need border staff, and one of the issues with St Pancras is the ability to process passengers through border control. So do you have additional staff at all 3 locations if so that it going to add to costs, even if staff can be found and probably wont happen, or do you redeploy from St Pancras which just makes St Pancras worse.
One solution to the St Pancras problem would be to reduce the time people are in the waiting area, and increase border control facilities there so that people can be processed and loaded on to trains more quickly. Maybe let them up on to the platform 10 mins before doors open, so that people can find their right carriage, this would reduce people in the waiting area.
Unless you have a complete rebuild at St Pancras, which is unlikely to happen on cost grounds, then the only thing you can do is make the operation slicker, assuming the average time spent in the departure and border area is close to 1 hour for each passenger currently (not sure if this is the case, certainly on my visits it seems like the right ball park), if this could be reduced to 40 minutes then thats an immediate improvement.
Or if they sold and marketed tickets that departs from Ashford at a lower cost than st Pancras or included parking/domestic train tickets from elsewhere. It would perhaps make Ashford more of a prospect
At what price point would people switch to Ashford? For people travelling from a wide area north of London St Pancras is the obvious choice. Anyone whose starting station is on the ECML, MML, Thameslink or with a short walk WCML would prefer to start from St Pancras. Could SE high speed services cope with even 1/2 a Eurostars worth of passengers and luggage per hour to say Ashford in addition to their current loading.
Although an attractrive proposition I cannot see it being commercially viable, and realistally its unlikely a furure government of any political hue will subsidise international services