Completely agree with Tinstaafl, bring back the 152 with a Rotax up front
The Rotax conversion already exists for the Cessna but needs a Hoffman constant speed propeller to make enough power for climb, and in combination with the engine itself would be an expensive package.
Typically small displacement engines making the same
rated power as larger displacement engines have a narrower rpm range over which they make that power. In an automotive context that means you use the gearbox more, and in the context of a heavy aircraft with a fixed pitch propeller, it means that it won't climb because the engine rpm is loaded down below the power band at best climb speed. The solution (other than a bigger, torquier engine with a wider rpm power band) is a constant speed prop that I think many would consider unsuitable for a basic trainer.
Auto leaning fuel injection and self contained electronic ignition would improve the 152s Lycoming fuel economy in a training role, where manual leaning is not typically used. I think that would be a better overall solution.
So to anybody who is used to the appearance of the Cessnas, the C42 looks flimsy and under-engineered. In reality, it's designed to virtually identical structural requirements as the other two aeroplanes, and thus just about as easy, or difficult, to break. Because those requirements are phrased in terms of g-loadings.
The issue with light weight construction is that not all stresses on an aircraft are generated by g-loads. They can also get broken being pushed around the hangar or when people are climbing in and out. Training aircraft do not operate in a laboratory environment.
I learned this lesson running design studies and building experimental hardware for Army customers. They tend to take your carefully designed structure, matched perfectly to its theoretical loads, and run it into a tree! And they need it to work afterward.