What people fail to realize is crypto is actually just code....open source code.

EOS is nothing more than another open source code project that can be taken and put elsewhere.

Just like we saw (or will see) Vice fork the blockchain and use SMT to create tokens on their fork, a tech Smeemit developed, the same holds true with all other code out there. The challenge is dealing with scaling issues which we know BTC and ETH have. They cant just grab code to solve that problem.

However, doing like @stan said, grabbing some code and creating a middle code, that is highly possible (well I am not sure from an engineering point of view but you get what I mean).

Networks overlay and interact all the time. That is what blockchain is. At some point, just like web browser brought interoperability to the internet, we will need to see something like it within the blockchain world.