You are assuming that someone would want to buy a church building for a price that is reasonable to the Church
Close but not quite.
I am assuming that the revenue generated from the building is less than the cost of it's upkeep.
If so, then it's not an asset, it's a liability, and as such, any money at all that you get for selling that gets you out from under it, is from a financial perspective good.
If you need the million quid that morningpaper cites, then it's actually rational to pay someone to take it off your hands.
(OK, I've studied finance more than may be good for me
If the building's activities generate enough wealth then I don't see why other people should pay. The CoE has huge assets in jewellery, art and nice houses for it's senior executives. Don't see why poor people should pay taxes so that they can keep those.
Even if a historic church building were sold to a secular organisation, that organisation would still be under obligation to preserve it, inside and out. Who would want to without help?
Regular stream of churches concerted to upscale dwellings. Most have land as well, things can often be done there as well.
Rather suspect that a few of the prietter abandoned churches will end up serivng the gay marriage market.
My own church is valued at about £400k. For us to find an alternative building, it would probably cost us over £5 million.
Lots of organisations find themselves in that position. Not just buildings. Many people drive older polluting vehicles with bad fuel consumption because a newer car is beyond their ability to raise capital. Even the most simple minded accountant could spot that one coming. When the money it stole from charities was spent, the CoE was basically doomed, though the sheer scale of the the thefts meant that it this would not show for decades. It's a huge momentum to deal with priest pensions, law suits for raped children, and clinging to an architectural legacy that would look out of place on a successful organisation.
As you say, some parts of it aren't fading away, and I expect that in the next 20 years or so the financial stresses will lead to schism in the church.
But we usually apply for whatever grants are available from the local authority for repairs to the churchyard.
That's fair enough ,where an organisation make a facility open to the general public, then some provision for it's upkeep. Churches themselves are not available to the majority of the community, so it's a different story.