EIP86 and abstraction discussion is exciting for the future, but what are the things we could change first, to allow a contract to pay for gas?
For example, for the withdraw transactions on BabyZoE, they claimed to solve this issue with cryptoeconomics -- I think here the intended recipient instead hands over the zero-knowledge proof (of coins being transferred to himself) to a user who does have sufficient gas, and this user then submits the proof to the contract, and gets a little reward.
However, this isn't possible in all circumstances, and malicious users could just refuse to submit the proofs, very easily and lazily DoSing the contract.
So in the meantime, before the metropolis hardfork and introduction of EIP86, what would be the minimum possible changes that would allow contracts to pay for gas?