2017-07-13 18:58 GMT-03:00 Dan Libby via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>:

If I understand correctly, my node will accept the incoming tx inputs
but obviously will not perform any segwit related validation, thus those
inputs are not fully validated. I don't yet understand how my node
thinks they are valid at all given that it does not understand P2WPKH
address format, so either it doesn't need to, or P2WPKH is somehow
already valid. I know this has all been discussed in the past, so if
someone can point me towards a document that explains it I'd be happy to
read that.

From your perspective, the P2WPKH will look like a anyone-can-spend transaction, thus, valid no matter who is spending. So, you would be basically leaving the security of segwit transactions to those who actually are interested in and using them. If your fork becomes popular, it would decrease the security of Segwit transactions to something akin to the security model of the Drivechain currently being discussed: only those particularly interested in that particular sidechain (and segwit witness could be loosely categorized into a sidechain) will be responsible to prevent others from stealing funds from the anyone-can-spend transactions.

Lucas Clemente Vella
lvella@gmail.com