https://github.com/ethereum/eth2.0-specs/tree/dev/specs/phas...
Vitalik is proposing a role reversal to take place earlier than it was previously planned (not completely accurate in a technical sense re: previous plans, but effectively the same):
Eth1 mainnet will hand-off consensus responsibility to Eth2 mainnet (PoW -> PoS), while Eth1 nodes continue to "run the code" that executes smart contracts / processes transactions.
If the plan is put into motion, and as long as some miners / mining pools don't yank the plug on their mining nodes in the canonical Eth1 mainnet, then the canonical mainnet — per consensus among the Ethereum Foundation and aligned developers, Eth2 validator operators, orgs/companies/exchanges/etc — will transition suddenly from Eth1 (PoW) to Eth2 (PoS). And that will be the end of all mining on the canonical Ethereum mainnet.
Miners/pools who find it impractical or undesirable to reallocate resources from mining to staking may band together to continue running an alternate mainnet chain based on PoW (ETW?); market forces would then decide whether that chain is viable, as well deciding the fate of the evolved (PoS) Ethereum mainnet chain.
I am not saying this EIP, or PoS, are bad. It's the way you do it that matters.
I know it’s tempting to discard miners’ concerns, but it would be a great mistake. Miners need incentives, without incentives we’ll start allocating capital and resources somewhere else.
We are not greedy, not crazy, not confrontational: we are just rational.
If someone don’t like us, then could do without us.