Ok, I'll go out on a limb and say that these will NEVER catch on. I'm not sure you could try and come up with a more monumentally stupid idea, and I am mystified every time I see an ostensibly knowledgeable person bring it up.
There are lots of reasons LNG vehicles are never gonna be a player, but the big two are infrastructure and competitive technologies. It would require massive infrastructure changes to make LNG vehicles sensible for most people, and when looking at that vs. competitive technologies, the benefits are approaching zero.
Gas fueled cars and gas/diesel hybrids go further, cost less and require zero change to existing infrastructure.
Plug-in hybrids and electric cars have somewhat less range, but the cost advantage comes sooner and the infrastructure is in place for most people (long-haul options like quick charge stations, battery swapping would help with getting more of these on the road, but really are not necessary).
Even if you are an efficiency/emissions nut LNG is just a really piss-poor alternative. It retains the inefficient internal combustion engine (but with slightly higher efficiency!). There is no conservation mechanism when coasting/breaking...
In fact the most infuriating thing about that article is the notion that municipal vehicles like buses and trash trucks were the hope for LNG!!! Those are the types of vehicles for which electric makes the most sense. They start and stop a lot...no combustion engine is ever going to hold a candle to an electric motor with regenerative breaking. Hell, use a big batch of supercaps and you can make these about as efficient as my little 2003 Mazda!
LNG is a colossal waste of time, money and energy. Granted, it is largely pushed by people in the natural gas industry and so I can't really fault old T-Boone, but when it gets passed on by people that should know better it is very frustrating.