For the LMT'D, certainly not fat tire. The 700 series will potentially support a 2.8" tire according to Kevin from Ride1Up, but he wasn't sure about a 3" tire. The same may be true for the LMT'D.
However, your subject of this thread asks an entirely different question that doesn't match up with your post. Will Ride1Up create a fat tire model? Based on the interview I saw, there was no indication of plans to do that, but it's possible. I wouldn't wait around for a company to design a style of bike that you are interested in, which may never happen, and instead look at bikes that actually exist.
I was considering the Espin Nero myself a while back, thinking I would get a regular tire and a fat tire bike, but then I decided to against it and decided to see how a 2.4" wide tire bike serves me and concern myself with a second bike later on. Just checked the early bird special on the Nero - it says there are only 7 left.