I'm not too bothered about these deals. If it gets to the point where we are sweating about losing a player with this clause then he's obviously going to have reached world class. We'd have a player that good for at least 3-4 years on our books, and if for example someone like Madrid or Barfa were to tempt him away then the clause would just put another €30m on the fee. €40-€45m for a player in this situation when you paid €9.4m for a kid who it seems many teams want and would pay a lot more for. If we didn't accept the clause we would most likely end up with a less talented player from Boca as part of the deal and be left with little value from that Tevez deal.
We get a bit wrapped up in fees and transfers but what players do on the field adds most value to a team. Anyway, the kid hasn't signed or played a minute yet, we'd be fortunate to be in a situation where we are worrying about the above. If he doesn't turn into a Pogba-level player then he's easily replaceable anyway.