Not in 'theory' it just would. If you vote for a party that promises to revoke article 50 in a general election then you are voting for revoking article 50. Not they have any hope in hell of actually winning an election. It might however force Labour to become more clear on their Brexit position. Kind of like the Brexit party will to the Tories. In my constituency I only really have a choice between Tory or Lib Dem so I vote Lib Dem so my vote is not wasted. Especially so because our current Tory MP is a complete moron and thought the most pressing problem in the area was motorbike noise on a prominent country road where there are probably at best a 200-300 hundred houses, the majority of which will be massive detached houses of rich people. So the twat wrote a four page letter to everyone in the area and commissioned an investigation to show everyone how importantly he was treating this 'massive' problem. Which just shows Tory party priorities.