Marketing. In a year or two I bet they do away with the XBones, also, only to bring it back after a couple years. By taking the Train out of production they are building demand for it again. In a year or two they will bring it back, and everyone will go "Oh boy! I better get one right now!!"
I believe it will be back, they took the Wide Glide out for a year and now it is back. I believe that in 2008 the only WG you could get was the 105th anniversary edition.
Well, hopefully when/if they bring back the Train, they don't turn it into an abortion like they did with the 2010 Wide Glide.
Getting rid of the NT was a HUGE mistake, in my opinion. It was the MOCO's flagship bike in the "Dark Custom" line. It also attracted the younger generation and modders because it's a classic bike and it gives off that "Bad Boy" image/vibe. Something it's replacement, the FB-Lo, does not accomplish.