I’m trying to think of the impact: no more transfer fee? Higher salary? Longer contract to receive a higher termination fee?

Able to buy out but this is the correct verdict as no player should be kept like this

Six month contracts, the clubs can terminate at every transfer window. If the players can just walk away, the clubs will find a way to do the same. No more running out your 5 year £300k a week contract, you’ll be out.