Low emission zone London 2012

I was reading an article in a national paper last week re getting ready for the LEZ. I, like a lot of people will have to purchase a newer vehicle if I want to be able to drive in London. The modifications are too expensive for an older van. Is Boris sure that there is not a loop hole that thousands of van drivers in London cannot exploit ? They did with congestion charging. I cannot believe all the 2001 and older vans will disappear overnight.
I like most business owners will struggle to become LEZ compliant. I think you'll see more small businesses go to the wall.