The Ethereum guys proposed something like this in a super long rambling document with lots of made up terminology [1]

https://github.com/ethereum/wiki/wiki/Sharding-FAQ

Yeah! We can also do 'cross chain atomic swaps'; A trustless tx that allows two chains to agree on a price. Either both sides claim it, or the money is returned to its sender.

There are quite a few projects working on "cross-chain" solutions:

https://cosmos.network

https://ark.io

https://omg.omise.co

And more

Ethereum sharding?

https://github.com/ethereum/wiki/wiki/Sharding-FAQ

Check out Ethereum's Plasma proposal: plasma.io. It's a similar concept. I'd describe it as tree of blockchains with MapReduce for state transitions and merkle trees for proofs.