^This goes against what some people are parroting, which is that Runaway Railway will use the exact same layout and vehicles as GMR. Suffice to say... what?!
Those vehicles can not move quickly and would be a strange fit for a "runaway railway". In addition it's a different kind of trackless (no wi-fi) than what has been brought up. That's different than what I heard which is "imagine Mystic Manor without the AAs and 100% more projection mapping and physical effects".
Granted, if it was the former then I totally believe it'll be up by 2018, but I even doubt Disney will push for that. I could see holiday 2018 at best, with spring 2019 as the favorite.