Gromit....UKIP are barely surviving with him, so without him its difficult to see how it could continue to exist. He is about the only sane person in the Party, not that that is saying very much. I am going to predict that UKIP will be a flash in the pan, just as the Referendum Party was before them.
Farage has said, on many occasions, that his only purpose is bring about a referendum on Britain's continuing membership of the EU. He has gone further and said that as soon as that is achieved, the Party's job will have been done and it can disband.
He appears to have his back up against the wall in Thanet. In 2010, the Tories had 22,043 votes, Labour had 14,426, Liberals 6,935, but UKIP had only had 2,529. Its a big ask for the people of Thanet South to abandon all those non-UKIP votes and put him in place instead.