There's a bigger issue here to my mind. With the loss of one if the 'big five' channels on Freesat it no longer looks quite so attractive to hardware manufacturers. Although three of the main TV manufacturers still offer Freesat in their TVs, we only have one manufacturer of Freesat PVRs, Humax, and if they decide not to follow through with the G3 box promised for late this year/early 2019 then I think that it's prety much game over for Freesat. The loss if the All4 app. is another major blow if you don't have any other devices that support it.
If you can't get a decent Freeview service, and can't get/don't want to pay for Sky or VM and rely on Freesat then you're stuck with SD, in much the same way as those Freeview users will be with the loss of BBC4HD when the changes bite for removal of the Com7/8 muxes.
In the short term, if C4HD remains FTA on satellite then it should still be viewable via the non-Freesat option on G2 boxes, but, as I recall (someone correct me if I'm wrong) you can't record it, and would in any event loose series linking. I suspect that the channel will end-up behind Sky's paywall, but if it doesn't then an FTA satellite PVR might be an option, after all, for the most part, Freesat is just one fancy EPG, with a bit of channel allocation change management bundled in.
The recent postings on the 'net lead to me to conclude that things have been left open for further negotiations, but given the sudden surprise announcements I wouldn't go holding my breath, waiting for things to return as to how they were.
As usual, it's Joe Public that gets a raw deal here. I suppose that you could email Freesat/C4/your MP, but I doubt that that will do much good.
As it happens, I think that C4 and the other supporting channels have gone 'off the boil' as it were, of late. Apart from watching a few lifestyle programmes with SWMBO I can't recall the last decent drama/documentary that we watched on any of the '4' channels.
I hope that the status quo that we know and value returns, but if it does, it may be some time coming. Much as I hate the idea, I can see a Sky subscription looming chez Dye .....
Clem