If the current library is something you really want to try out, I'd say go for it. With how little is known about the NX currently, I wouldn't let it impact your purchase, and considering that it hasn't even been formally announced, it seems to me it's unlikely to even be released until end of next year. There's also the fact that backwards compatibility isn't guaranteed (though I personally hope it's there), so you might be waiting to play certain game(s) to no avail.
It also depends on what your disposable income looks like, and if $300 to be able to play the games you want a year early is worth it to you in terms of your gaming budget. I personally love the system. Even as someone who generally doesn't care for Mario games, I still have a crazy amount of great games to play. Works as a great media hub/remote too, but if you have other platforms, that's probably a non-issue.
Anyways, it really depends what you're looking for, how long you'd be willing to wait, and how much you're willing to pay. Good luck making a decision!

NNID: Zephyr25 / PSN: Zephyr--25 / Switch: SW-4450-3680-7334










