'The conservatives will have carried out UKIP's main drive. Am I wrong?'
It all depends what happens to the COnservative party. The Conservative party as it is now under Cameron and the team is not really conservative as everybody knew it. It is Blairite rather than Thatcherite.
If Leave win, then the Tories will ditch Cameron and much of the team, and change. However, I doubt they will really change much because most of the until recently were part of the team and went along with the team's objectives.
That is why UKIP grew, because it fills the gap for common sense conservatives who did not agree with the team and the hugging of hoodies etc. So UKIP can only grow, particularly as the Labour Party is led by Corbyn and a challenging bunch of graduates from Oxbridge who do not realte to millions of ordinary working class voters who used to be their traditional base. Many of those people will prefer common sense UKIP over claptrap Corbyn or the Oxbridge Labour team.
So UKIP has a real future as a populist, common sense party of ordinary people combining the good things of Labour with traditional common sense conservatism and ditching the hoodie hugging Etonian Oxonian Cameron and the team stuff.
But, the Establishment does not want a people's party, a populist party, because it can't control it, so I think they will destroy it and we will back to the usual TweedleDee and TweedleDum.