I have thought for a while now, that Chelsea would need a healthy lead going into this stage of the season, because of their run-in. Last three away fixtures are at Man U, Spurs and Liverpool. Our problem is that we "don't travel", and have become a bit predictable away from the comfort of Stamford Bridge. If Chelsea don't win the title this season (and I don't think we will), I don't believe the title will go to The Bridge for quite a while. The squad is ageing, and a complete overhaul will be necessary over the coming couple of seasons. Terry, Carvalho, Deco, Ballack, Lampard, Anelka,...the list goes on are, I believe "over the top", and will need replacing.
Sorry, I'm waffling. In answer to your question: it wouldn't surprise me if Arsenal caught Chelsea for second place, catching Man U might be a different proposition.