One for the future, he's Kev 2.0, best for all involved if he stays at Leverkusen and develops under a good young manager whilst De Bruyne is still performing because he'll cost the GDP of a small African country and won't want to be a back up.
I can definitely understand this argument, but we saw last season that Kev surely isn't gonna be able to cope with a full season, game after game, every few days. He could easily pick up an injury or two, and even if he doesn't, he's gonna need some careful game management from Pep to avoid the same kinda burnout we saw at stages of last season.
I think he'd benefit massively from having a young, similarly-skilled back-up to come in for the last half hour of games or start against some of the weaker sides to give him a rest. Yeah, Phil could fill that role too, but Pep hasn't shown huge willingness to play him there, and Alvarez hasn't quite looked like he can fill that role, either.
Bring in Wirtz now and suddenly we've got a young lad who not only gets a relatively comfortable year easing-in to the system and figuring things out in the Premier League without excessive pressure on his shoulders, but also gets to learn from the very best player in his position, along with the best manager, and would surely get plenty of game time, too. Makes a ton of sense all round, for me.
But, to be fair, can also see the benefit of him having another year in Germany, starting each week, honing his skills. Only problem is I'm sure he'll have another brilliant year under Alonso and be worth even more next summer, with a few more clubs after him too.