You stop getting attached to the idea of a singular manager taking us from very poor to elite.
For now, the job at hand is to implement a modern, sustainable way of playing will help us control games more often. Most top teams have shared basic principles. We need to be on that same page - establish the foundations. This is, right now, the most important thing Amorim can do.
We stick with that manager until he hits his ceiling. When he reaches that ceiling, you look around and try to get a manager to take that next step while still keeping those foundations. When that manager reaches his ceiling (or makes us worse) we move on.
You can't control whether a DOF, Manager, Player, set piece coach works out. You give them a fair crack, look at their work objectively, and if they're not up to scratch you move on until you win big trophies. That's how top clubs operate.
Luckily, it's usually pretty obvious if the type of football a team is playing is going in the right direction or not. It was obvious Arteta and Klopp were going to make a top team. People like Amorim, Xabi Alonso, Nagelsmann, Iraola, McKenna and Frank are very good coaches and it's obvious. Whether or not they can translate that to a top team, you only ever really know when (if) they arrive there.