It would make a lot of sense if Neko mirrored
http://hashlink.haxe.org/ in the future and certainly it's ment to be a successor and there are plans to keep providing Neko support, the exposed API seems to provide access to main loop timer something that NME had to do for itself, there is a haxe issue thread discussing the addition of main loop timer stuff ready for hashlink. I suspect for any graphic UI you will most likely still need a sdl and ui haxelib alongside neko, such as Lime or similar currently provides, I would presume that Hashlink will get support first. Haxe normally favours the haxelib battery approach so it's not likely that full ui will be in neko by default.