Agreed, if EY look at a new UK route it will be EDI, it has been rumoured to restart in 2024.
For BHX, I suspect QR will eventually bring in a bigger aircraft or go twice daily on the 787 and I can see Saudia doing more upgrades to the 787-10, availability permitting and perhaps adding another frequency.
In the long term, Kuwait Airways may be a possibility, they have vaguely mentioned BHX in the past. Gulf Air at present simply don't have the aircraft availability and Oman Air haven't even returned to MAN after the pandemic.