Personally, for me I’d like to the introduction of a spending cap. Each club has the same amount of money to spend on players, transfers, wages, agent fees etc (say £300m)
If a clubs revenue does not equal the spend, then the owner, if they wish can pump money into the club to cover the difference. If the owner doesn’t, then they operate within their budget/revenue generation.
Profits on revenue vs income can go back into the club (u23, woman’s team etc). And any breach of up to £10m over would result in a transfer ban for 1 window
Whether your Luton or City, £300m is your limit