But not all nodes will update to recognise segwit. If a non segwit node receives the two records that signify a segwith transaction, then won't it accept the payment record, but reject the signature record as an invalid type. It will accept the payment record as valid because the signature will be blank ie. anybody can receive.
Yes, but for a full node that is segwit capable, it WILL receive the witness data. Once segwit updates, running a full node without segwit should not be optional and is less secure since that node cannot verify the signatures of segwit transactions.
I agree, and I believe it is effectively mandatory for miners to run segwit nodes. The beauty of segwit is that is is not a requirement to update a node to be able to use a core wallet. You can't verify the signature of course, but you can still receive a segwit transaction and accept the payment as an "anyone can spend" transaction. The signature has to be completely blank, so it can't be hijacked through the base transaction, and a segwit node will verify the signature record for you. I assume that if one wants to update from an old version of core to a segwit version, one will have to update the latter part of the blockchain to include the signature blocks.
I've only seen the 50% discount on transaction fees mentioned in one place. Is this definately going to be an incentive to update to a core segwit capable node?
