So a good chance of the current two daily sets being ramped up over the summer?I hope it won't be put back, and I don't see why it should be. The relevant drivers and TMs along the route sign HST's already and it would appear the government wants longer trains to run in order to maintain social distancing as much as possible. The final set is ready, the only thing that I imagine might cause an issue is the readiness of the two spare ex LNER power cars shich are being fettled at Eastleigh in readiness. I've not heard how things are progressing there, but they've had them a good while now.
Edit: I've forgotten how many sets were out daily pre-COVID-19. Think it might have been 3 with the exception of Fridays and Sundays when 4 were needed. Always at least one spare.