#2 Better race circuits in Britain exist
Brands Hatch. Donington Park. Rockingham Motor Speedway. There are F1 ready circuits in Britain and they come with a racing pedigree.
Even if Silverstone ends up on the chopping block, one of these tracks can readily take the place. While London is a world-class city with a possible track that will have iconic monuments like Trafalgar Square, it will be a project borne out of haste.
Rockingham has excellent views for fans because nearly all of the circuit is visible from the grandstands. It would need redesigning before an F1 race can take place though.
Donington and Brands Hatch are not currently up to modern F1 standards, but Liberty has done a great job in reviving the Méxican Grand Prix, so it can be done.
All it needs is minor tweaking rather than major infrastructural upgrades. Better race circuits exist if only Liberty Media looked with an open mind.