That Guardian comment is getting widespread attention, but in reality I think it's also possible to look at Cameron's non-invocation as a real opportunity. Don't forget that Boris' original position was that this referendum would only be the start of a renegotiation with the EU - and that only a "no" vote would get the attention of EU leaders such that a true discussion over changing terms can take place.
I don't think it's outwith the realms of feasibility that, behind closed doors, our leaders could talk to Merkel and co and get a promise to have a new treaty that aims to return some sovereignty to member states (not the UK alone, but everyone) - and a permanent delay to the triggering of Article 50 would pass parliament. In the meantime - we stay in, and nothing changes.