How is your knowledge of vector math, matrices and quaternions? And are you as good at 3D modelling as you are at 2D art?
Every time anyone suggests 3D features, I think they are totally missing these two points. When we added the multiplayer feature to C2 it was a significant lesson in how everyone imagines it being perfect, a dream come true, you'll never need to learn anything, it will be so easy! But in practice it's still hard work, and I don't think you realise just how many obstacles there will be in your way, even with a tool like Construct 2 doing a lot of the heavy lifting for you.
I personally would just like to be able to include 3d models, like we used to be able to in CC, and just build a map from 3d objects and in 3d space, but the game would still just be 2d and using current collision boxes.