"Otherwise known as: 'Selling the family silver' for short term gain."
Always a danger of that, but I'm sure councils (and businesses) can identify 'assets' that are 'underused/(genuinely) surplus to requirement'.
There may also be things that could be used better by local groups/community rather than just sold to the highest bidder.
Worst case is where building/land is sold and the new owner adds significant value by change of use through the planning system.
Would like to think that CEC would sell some things 'with planning permission' or have some sort of profit share clause (unlikely).