There are reports that the DUP are refusing to work with the Conservatives any more unless Theresa May is deposed as leader. This means the following scenario, while very unlikely, is possible:
1. The Conservatives vote to keep May as leader, and she keeps pushing her Brexit deal.
2. Support for them plummets, while support for UKIP goes up greatly.
3. Labour calls a Parliamentary confidence vote in the government.
4. The DUP vote with Labour, and the government is defeated.
5. An early election then has to happen.
6. The Conservatives are wiped out in the subsequent election, reduced to a LibDem-like handful of seats.
7a. Funniest (but remote) possibility: UKIP win the election.
7b. Not quite as funny, but still funny, and not quite as unlikely: UKIP win a swag of seats for the first time, and become a major party.