What are you trying to say? First you suggest that RM are stockpiling players and then you suggest us to loan Reguilon out. Loaning is more like stockpiling then selling with buy back clause.
The player is totally in control now. If he does not want to return to RM the clauses means feck all.
With Loan the player is forced to comeback.
What are the odds on that thought? If the player doesn't agree to it then it can't be included in the deal, and by agreeing to it they obviously hope it comes to pass!
I don't know how many similar deals Real Madrid have done but i'd hazard a guess in most cases they expect to sign the players back, either to go in the first-team, or sell on for an even higher fee(Casemiro/Morata)
But going forward it's open to abuse as well, say Madrid have a dud they want to get rid of, they'll always get interest in them because they were at Madrid in the first place, they get few clubs sniffing around, Madrid quote a figure the clubs are prepared to pay but add a buy-back clause with no intention of actually activating the clause, and the interested clubs think we'll they(Madrid) only add clauses to players they plan to bring back so he might be even better than we thought he was and pay more for the player than they initially planned too to get the deal done ahead of other interested clubs.