Combining game code from same Developer

I didn't find a thread for this specifically but i had a theoretical question. I've been playing fallout 4 for a while now and I've realized it is just like Skyrim. bethesda developed both these games which you can tell because of the recycled sound effects and also the gameplay is nearly identical. anyway, since they appear to have been developed similarly, couldn't you Frankenstein the 2 games together? maybe add the dragons from skyrim into fallout 4, and add the fat man mini nuke launcher as well as the brotherhood of steel (and their kickass blimp) into skyrim. I think it would be really awesome to have a crossover. i don't really know what I'm talking about when it comes to games and their codes though. anyone else think this would be awesome?

Whoa. Well that would be hard.

Check out, a mod that combines fallout 3 and new vegas, two games made by different developers.