Solution for who? Everyone with power in this situation wants to keep the building valuations artificially inflated.

If local people want shops on their high street then the only real solution is incredibly agressive fines for vacant commercial spaces.

The commercial market is functionally frozen and illiquid. Owners can’t come down without declaring bankruptcy, bankruptcy is bad for lenders because they can’t move the property for the loan amount so you essentially have a mass delusion because accepting reality would bankrupt much of the existing players and start a crisis