All good things have to come to an end at some point and I think that the Top Gear team have struggled to come up with the sort of ideas they used to in the last couple of series. The budget cuts they have had to deal with can't have helped. When you consider that Top Gear is a big earner for the BBC overseas cutting the budgets was a pretty stupid idea as the Beeb must get a decent return from the program.
I suspect that at some point in the near future James May will wander off to do more of his own style of TV shows(which are usually very good) as will Richard Hammond. Jeremy Clarkson has tried to diversify in the past and largely failed. I suspect he could probably afford to semi retire and just churn out the odd juvenile DVD from time to time.
I like Top Gear; its one of the few shows on telly where the presenters aren't afraid to be politically incorrect and offend a few people. We need a few more people being stupid and generally speaking their mind on telly. I shall miss it when its gone.