Great news! I am very excited to hear that! It is good they stay with the html5 engine, because there are enough options (like Unity, Godot, GameMaker) if you need native code already. The most important for me is that they improve the performance of the C2 Editor. My wish is that they implement some kind of "pro mode", where you can dive deeper in the code for fine tuning.
Anyway, C2 is a great tool i don't want miss anymore and C3 will be even better!