Germany MIGHT be able to beat France
Let me start by saying France is realistically still the best team and the favorites to win the U-20 World Cup. However, from the way they've been playing so far, it wouldn't be entirely implausible for Germany to beat them or Japan and win the whole thing.
First, France only beat England by one goal. Now, whether or not Germany is better England is anyone's guess, but they should still be relative as two of the world's best footballing nations. This means that the gap between France and everyone else isn't as large as "best team in the world" might lead you to believe. England also most likely doesn't have a New Gen 11 forward, meaning their goalscoring capabilities wouldn't be as good as Germany, who has Michael Kaiser (who scored three goals, one of them being a hat trick).
Now, as for France vs Japan, the performance from the French team has been underwhelming. They are playing against the clear underdogs, most of whom have no experience playing official matches for their nation (except Aiku but he's selling lowk). Despite this, they are only a goal up, and their midfielders are outscoring their forwards. The team seems heavily reliant on Hugo, who's been doing 75% of the work for them. Julien Loki, the supposed best player of the tournament, has basically been a non-factor for most of the match. It also seems unlikely that France will turn this into a blowout as Shidou will probably also score this match.
It wouldn't be very surprising or crazy to me if Germany were to beat France and become the final boss or win the entire tournament. We've also been getting a lot of Kaiser moments sprinkled in lately, and the creators themselves have stated how he'll be getting more development soon. I expect that Kaiser would become a powerhouse striker during this arc with the help of Ness, potentially even rivaling or at least relative to Loki. (Noel Noa did believe that Kaiser could surpass Loki after all)
Kaneshiro absolutely should've made this match into a blowout for France, but instead decided to nerf Loki for more tension. If Itoshi Sae was playing for Japan right now, they would very likely be equal to France or even in the lead. It hasn't been a great first impression for France so far, and I can't help but wonder if Kaneshiro is nerfing them so their potential defeat later in the arc wouldn't be as unbelievable.