I agree. For me code swapping is such an important feature. I can't imagine how people are doing game development without it. On the other hand, there are a lot of games for mobile devices, so I guess it's not impossible...
Like we always did.
Compile, re-deploy
Actually, it's not so bad. Libraries like libgdx allow you to target native Java and the phone via the same API. You can easily do 99.9% of the development on your PC and then deploy to phone to fix a few shader bugs here and there and be done with it.