I am wondering how compatible this game will be with Edge of the Empire, Age of Rebellion and Force and Destiny. Will you be able to take elements of those games and just plug them into Genesys? If I am playing a space opera game and need a light freighter can I just refluff and use the stats for the YT-1300?

We don't know for sure. They are making some changes--including some tweaks to the vehicle rules--but the extent of those changes is unknown to us. More than likely, the changes will be small enough that adapting something like a light freighter will be easy, but we'll just have to wait and see.

To follow up on Blackbird, there will be discrepancies, but nothing greater (I expect) than OD&D to AD&D.

I almost hope there will be compability issues, at least when it comes to specializations

My guess is that things will be very similar when it comes to "run-time" rules, but quite possibly different in character generation and such.

That is, a Genesys and a Star Wars character might both have Intellect 4 and Mechanics 2, so they roll 2 yellow + 2 green dice to repair something, but the process by which they come to have Intellect 4 and Mechanics 2 might differ.

I am thinking for the most part, will be very little changes but nothing that will be a major change to both systems.

I know it will be similar but I hope it feels a bit different. I already own all the main Star Wars books and don't want to feel like I'm buying the same rules book a fourth time.