Chelsea have been doing the same for much longer with their huge loan system. Kind of feel transfers are heading in to a new era of buy-back clauses being standard and massive sell on percentages being inserted into young player's contracts. If you think about it, it's an impressive business model because you sell a player like Maffeo for £8m (already a solid fee) and you have 25% of any future fee in the bank. Unless he stays at his new club for his whole career, you're likely looking at at least another £5m (and likely much more if he develops well + transfers keep inflating). Pump out a few top young players from your academy each year, ship them out with big sell on percentages attached and you'll be laughing. Chelsea had it wrong, they hoovered up talent and sent them on loan to develop them & sold those who they felt didn't cut it. I feel City will be open to selling their best young players who could potentially make it at the top level because it's a longer term investment & they can just go out and buy an established player who is 'plug and play'. Worst case scenario for them financially, Maffeo becomes a truly elite player and they want him back, they only have to pay 75% of his transfer fee if he hasn't moved.