Ireland could still vote either way (despite the propaganda the EU has flooded them with) but there could be another way that Lisbon is taken down: with the help of Vaclav Klaus. David Cameron has written a letter to him in support of Klaus' position of not signing the treaty, promising to hold a referendum if it has not been ratified.
If Klaus and Cameron pull this off, could it be a modern day Thatcher-Reagan pact? In fact I'm quite interested in Ashley Fox MEP's comment on ConservativeHome that the Czech MEPs in the ECR are saying that Klaus is simply going to refuse to sign it. For the UK to withdraw ratification of the treaty would surely be its death knells, due to the UK's sheer economic weight. It should have been put to the people in a referendum across Europe anyway; it is about the transfer of political power (and we had referendums for elected mayors).
But what if it is ratified when Cameron comes to power? I will ignore UKIP and co's arguments that Cameron doesn't want a referendum as scaremongering, but would it actually be possible for revision after ratification? This being the EU, probably not, but it would take a strong man to stand up and withdraw ratification unilaterally (and potentially be acting illegally). A more sensible promise would be to promise a referendum on the Lisbon Treaty if it has not been ratified, and a referendum on EU membership (since they have ignored the will of the people) if it has been ratified. Not only would that get the Eurocrats worried, but it might stop Lisbon too.