I really think Construct 3 should be focused on being the best 2d visual editor/visual events platform it can be.[...]
Construct 2 is a great basis for all this, but please don't waste time/effort designing for 3D. If I wanted 3D would use Unreal engine (which already has event driven support called Blueprints) or Unity 3D (which has well developed plugins for Events). Do not put yourself up against these behemoths and focus on making 2D game development the best.
That is exactly what I think too. If something like 3D has to be, then I think isometric (2.5D) and/or Super scale ( Afterburner, Outrun, Space Harrier etc.) is much more appropriate.