Simply put, if miners see a large majority of nodes signalling their intention to begin ignoring non-SegWit blocks their choice will be simple: mine with SegWit and follow the economic majority; or mine BU and dedicate hash power to a chain that is ignored by a vast majority of nodes.

As the activation date approaches they will see that it is impossible for them to mine valuable coins unless the support SegWit.

We need UASF support for SegWit so that we can all signal our support for it and get the miners to back down. UASF should in fact become a regular activation method to keep miners in check and show them that their centralized power is worthless against decentralized users.