Quote from: praxeology on April 18, 2017, 04:04:43 AM

jonald_fyookball,

Above in my reply I propose a way that non-upgrading miners could continue to mine non-segwit blocks while still verifying SegWit blocks, which would avoid a chain split. You claimed that such was not possible, I showed how it was possible.

You are misinformed.

Even with majority hashpower behind segwit, a non segwit miner cannot verify segwit blocks.

From bitcoincore.org:

Quote

so you may continue producing non-segwit blocks indefinitely. However, once segwit activates, it will be possible for other miners to produce blocks that you consider to be valid but which every segwit-enforcing node rejects; if you build any of your blocks upon those invalid blocks, your blocks will be considered invalid too.

The implicit assumption here is that the minority non-segwit miner will rejoin the main chain and not split off. If the segwit chain is the minority hashpower chain, they will either have to abandon segwit, or split off.

Segwit transaction types are meant to be backwards compatible, so the first block will validate, but later on, the outputs and inputs will be different. As soon as a transaction is sent from an address with an insufficient balance, that's when the split will occur.