Hard to tell if there's potential here. First, if Jon doesn't have financial resources beyond what he raised, it would likely be hard to find a lawyer willing to take the case.
On top of that, the crowd funding nature of this makes the possibility for success difficult to predict. On one hand, if he had used a crowd funding platform like Kickstarter or Indiegogo, we'd have no claim as those are very clear that funding is at risk of loss & successful production might never occur. However, Jon appears to have done it via his own site and thus it could be argued that backers were not sufficiently apprised of the risk. Further, his continued postings of "progress" and plans as well as the lack of being upfront on his website (the FAQ still says delivery in Feb while the home page says late 2016) could convince a judge he was or is behaving fraudulently and make a judgement in the complainants' favor. But that just takes us back to where if he doesn't have assets then there's nothing to be gained from a judicial award.
My personal feeling is this is more about competence than fraud and the $ aren't large enough to make it worth pursuing. He's most likely burned through much of the 700K he raised, not likely there's a lot left to get us even pennies on the dollar, especially after legal fees.