I'm way more excited for Reguilon than for Bale - with the slight caveat that the buy-back clause means we always have to worry about him going back to Madrid.
Make no mistake, this guy is absolutely phenomenal as a left-back. Best left-back in La Liga last season - intelligent in his runs, pacy, tough when defending, a real attacking threat...the complete package. Watched him quite a bit, never once did he have a bad game. The difference between him and Davies will be night and day.
The only reason Madrid are letting him go is because, while he's capable defensively, Mendy is a unit at the back, and they prefer a more defensive LB to a more attacking one, which Reguilon is. But in two years, when Marcelo goes/retires...if Reguilon develops like I think he can, this bloke will be top of their list. That's a worry.
I'm less worried about Madrid recalling him to sell on somewhere else - they've generally refrained from doing that, even when it involves their direct rivals (they had a buy-back clause on Mario Hermoso when he was at Espanyol, but didn't exercise it, and he ended up going to Atletico Madrid). I think their president called that sort of thing 'human trafficking', so safe to say he's not a fan of that.
But I do think Reguilon is every inch good enough for Madrid even now, and will be more so in two years if he doesn't get injured and keeps developing. Which is why this concerns me - they might well buy him back to keep him. Otherwise, phenomenal buy.