They can be. Will they be? I'm not sure I trust Britain's current political culture to do so, but I'd love to be wrong about that if a UK poster would like to correct me.
The tendency currently is to maintain notable churches that are no longer used as churches through the Churches Conservation Trust, which was set up back in the 1960s. The Church Commissioners transfer ownership, and the CCT then maintains the buildings and allows their use by the community: a good example is
St Mary's in Shrewsbury. Generally these churches remain consecrated. This is a
much better model than having former churches taken into state ownership or whatever,* but that's something that could only happen after a Jacobin-style disestablishment which is presumably extremely unlikely.
*We have an all-too recent example from France of the fact that the State is not, in any country, a good owner of this sort of building, at least not directly, even when if the building is still used as a church, let alone not...