It wouldn't even. Khan has pulled some masterful trick - the only people who aren't fooled by it are non-casual British boxing fans - he has those in the US believing he is a massive star in Britain and that his fights will sell large PPV numbers there. He has people in the UK believing he is a big star in the US and in Asia. If any of this were true, people would be lining up to fight him. Fact of the matter is that the only Khan fight the UK is that interested in is Kell Brook - and that's because we want to see him sparked out again. Whilst a fight with Pac would be a PPV in the UK, it wouldn't sell massively and the numbers involved in UK PPV isn't what people believe it to be either. It's usually priced at a maximum of £20 (about $30 USD) and won't do great numbers.
Wait, am I missing something here? Didn't Khan recently walk out of negotiations with Pacqiauo, claiming it was taking too long?
Khan's size and physical attriutes = an aging fighters nightmare. The only problem here is the fanboys making excuses as to why not to fight Khan when the reality is that they themselves know the truth. If you're at or nearing 40 years old, you don't fight Khan.
Khan's best wins are over aged fighters, or fighters who lost when they stepped up. Judah, Barrera, Alexander, and Malignaggi. When he fights a prime fighter, he struggles or loses. Garcia and Algieri.
Only a Mayweather or Marquez fight make Pacquiao more money than a Khan fight. Pacquiao fighting anybody else signals to me that he considers Khan a threat not worth taking.