Hybrid POW Pre-Proposal

@karalabe proposed an interesting compromise on Twitter. Read his Tweet storm for the rationale, and other comments on that thread.

Shower thought: ProgPoW is nice, but it runs the risk of a net split. How about a hybrid PoW?

A HF would enable an Ethash/ProgPoW mix (initially 100% Ethash / 0% ProgPoW). Each block could move the ratio by 0.1% in either way. The ratio defines what PoW the next block has.

Is this just about protecting investment in E3’s and A10’s?

It would be useful if those invested were honest about what they have at stake. E3’s are are dead either way and if no ProgPoW A10’s pushed out in weeks.