Mark Friedenbach, a bitcoin core developer, proposes a new idea he is calling Forward Blocks, for Bitcoin. It enables all sorts of amazing capabilities via soft-fork. You can read the whole paper here ( http://freico.in/forward-blocks-scalingbitcoin-paper.pdf ) and I believe he will be presenting it this weekend at Scaling Bitcoin.
Here's a snippet from the paper that does a great job summarizing a lot of the potential improvements:
We demonstrated that the idea of forward blocks provides a unifying mechanism that:
• Provides on-chain settlement scaling of up to 3584x current limits as a soft-fork;
• Provides for an (optional) proof-of-work upgrade as a soft fork;
• Limits growth of validation costs with a flexible weight limit;
• Decreases centralization risks through the adoption of sharding; and
• Provides a framework for ledger accounting in future protocol extensions including but not limited to:
– A rebatable fee market with consensus-determined transaction clearing fee rates;
– Confidential transactions for obscuring transaction amounts;
– Mimblewimble, ring signatures, or anonymous spends for obscuring the spend graph; and
– Sidechain value-transfer mechanisms.
While there are many moving parts to this proposal, it is not beyond the level of complexity of prior extensions adopted by bitcoin (e.g. segregated witness), and achieves a variety of benefits comparable in magnitude.