UKIP need MORE air time, not less. If they do, you'll end up with one of two things:
1. They'll reveal themselves to be a bunch of halfwits, like the BNP made themselves, or;
2. They'll actually have to have more than one policy, and will become a credible political party.
As it stands now, you have two extremes. You have the people voting for them because they're not Con or Lab (yeah, that worked out well with the LD last time folks), or labelling them as a bunch of racists and not taking them seriously (which is just as bad, as some of their political viewpoints are sound). They've fallen off the wagon a bit in the last few months so Farage will need to do some serious PR, but both the main parties should be taking them very seriously. Con as they're stealing their base support, and Lab as everyone in Scotland is going to vote SNP so they run the risk of having even less.
In answer to your question, I can see Milliband having to do some serious backpedalling and doing a deal with UKIP. People with short memories are going to leave the Cons out to dry, but Milliband is such a useless leader that he's making it very hard for anyone to vote for him. It's a tough one to call this year, that's for sure.
"Chav kids are like sand people. They're easily startled but they'll be back, and in greater numbers."