The developers have said that NXT will exist for another 3 years but he fully intended to replace ardor. If you want to invest in a long invest in ARDOR.
At the end of the year if you go kids chain ARDOR the price will fly up. I think in intervals 2 years ardor will cost $ 100.
Ardr team says that main development of ardr completed. Now some cosmetic and bug-fix updates only. They must pay attention to marketing more and more. Ardr platform is ready-to-use for ICO and business applications. I wait for $100 by the summer