[Brekkie]

It's pretty easy to switch the two PSB channels, especially if the BBC shut down their HD mux which could then effectively give ITV and C4 their own mux each. It's not an issue if +1 and smaller channels remain in SD.

Without losing any Freeview channels if they converted all muxes to DVB-T2 with a mix of HD and SD on both they could easily switch around 30 channels to HD only.