There is word that Europe would get the 2018 WC under the rotational system and England would be in a position to bid by then. http://news.bbc.co.uk/sport1/hi/football/3740851.stm
We'll have a fairly good chance. The new wembley (surprisingly) is going well, and if Arsenal, Liverpool build new stadiums as well we'll have a lot of large, modern stadiums. It'll be too soon for Germany,France and probably Italy to get it. That doesn't leave that many possible rivals. Spain? Our achilles heel, as always, would be London's transport problems.
Spain would be a real threat for any bid in 2018. Madrid has a very strong bid for the 2012 Olympics and Spain were unlucky not to get Euro 2004 ahead of the Portugese. They'll surely bid again for 2018, but I think we'll have a very good chance though, as David Will pointed out the FA have learnt their lessons, Euro 96 went well and our stadiums by 2018 will be superb with the new Wembley as the 98,000 capacity centre piece for the final.