The BBC keeps pushing iPlayer. I have seen (can't find the reference) mention that their eventual aim is to shut down broadcast and put everything on line
The BBC have seen the writing on the wall. Mobile broadband keeps insisting it must have all the spectrum in the world otherwise the earth will stop turning on its axis. First we lost 800Mhz band and then 700Mhz band. The UK is in a weak position here because we have a lot more terrestrial TV than the rest of the world, so most of the world doesn't give two hoots about the spectrum being re-allocated to mobile. When we were in the EU they were obliged to negotiate to keep that spectrum for TV on our behalf, but we've thrown away that support we used to get.
And at the same time as Freeview spectrum is decreasing, the BBC want to start broadcasting in 4k. Even with the HEVC video codec that needs twice the bit rate of 1080i using AVC. The BBC have to go to 4k, if they don't eventually they will become irrelevant as all cable and satellite goes 4k. But Freeview is never going to provide the spectrum for 4k channels, even a DVB-T2 mux can probably only fit two or at most three 4k channels in. And such muxes would be incompatible with existing TVs and STBs, and we've seen with the slow HD rollout just how long it takes to get all the old TVs and STBs replaced. There are still loads out there that can't even receive DVB-T2 muxes. It would be foolhardy of the BBC to propose another incompatible change. So all they are left with is streaming for 4k.