NX should just evolve as a platform to solve the problem of "yeah but if its released early it will be outed".
Release a new NX model every 2-3 years. If you have an older model, make the design of the hardware modular so its easy to just plug in an upgrade.
Release an NX more powerful than the PS4-XB1 (3 TFLOPS) in 2016.
Release an NX that can then run games at 4K (NX 4K) in 2018. Not everyone will want/need 4K, give the consumer the choice.
Once you buy any NX device you set up an account and your games are tied to it, and you can seamlessly upgrade when and how you want, no problems, your library goes with you, and lower end graphical games can be shared on the portable for good measure.
1994 was 22 years ago, since everyone cites Sega as a reason why you can't have different models. The industry has grown up and changed a lot since then, consumers like choice in everything (multiple iPhones, iPads, Macbooks, Android phones .... you choose what you want) and most gamers today are adults with their own disposable income, not little boys. Nintendo should embrace that, if they play by the old rules they'll be too predictable for Sony/MS to hit.