If Boris wins, and he starts as favourite, then what he does in his second term will be fascinating and the best guide to his future plans. If we see Boris becoming an increasingly national figure and championing causes dear to the right—free enterprise, low taxes and Euro-scepticism — it will suggest that he is at some danger of being decapitated by a Frisbee.
One thing worth noting is that with the influx of new MPs, the Conservative parliamentary party is far more pro-Boris than it was. It is now possible to imagine him making it through to the final round of a post-Cameron leadership contest should he return to parliament.