Guys,
There's a fundamental incompatibility between EAGLE and Fusion, and it's something that has needed to change in EAGLE anyway:
The whole focus of EAGLE is to design a board, where the focus in Fusion is to design a system. To be properly integrated, EAGLE needs to have a system construct that consists of multiple "boards" (or whatever term), connected with cables. Imagine the design rule editor being able to figure out that the cable schematic has a set of wires crossed, as the signal names don't match up. Or that two connector part numbers don't allow them to be mated, given the parts the designers have (perhaps separately) designated.
"Boards" (along with their accompanying schematics, BOMs, layouts, specs, etc.) should be migratable to a public place where they are usable by others in their projects, but cannot be modified except by the owner. I'm sure Fusion has these sorts of constructs.
Thanks for your consideration!