That is... quite a bit of development. Still prop planes would hold a good chance against Jets even if they are Korean war era...ish. I mean, the American P-80 Shooting Star top speed was around 898kph when armed for combat. 

A BF-109 K-4 (Which I assume Prussia would probably be using... or at least one very similar) has a top speed of around 720/710km/h, and has better acceleration, turn time, and climb speed would still be able to put up a good fight against it. The P-80 would have to line up, shoot, and then get away as fast as possible because if it missed(or hit, even then it was only .50 cals) all the cards suddenly went into the BF-109's hands. All the BF-109 has to do is hit the P-80 once with it's 30mm cannon and that thing is going down.

Though, jets do have excellent energy retention compared to prop driven planes. When it turns, it may have a massive turn radius compared to a prop, it can keep it's speed up in that turn and get away.

I'm mostly saying this for Village since he doesn't have jets, and is facing jets. 

Jets are cool, but in the end were only good for short quick passes instead of full out dogfights, which they would lose against props.