Would be cool to be able to open file from Tinkercad and Fusion360. Sure, you can download your own files from those places, then load them in. But if I am collaborating with coworkers, I don't want a thousand different versions of the same thing on my computer. Loading in from one of those accounts would increase productivity. Maybe you could do plugins? Each new site that comes out that handles files like these, you could add a plugin to interface them and let us choose which ones we want to install.
Maybe that's just me, I do pretty high volume printing.