It’s up to you, major games are still playable on old 3ds, just like pokemon and monster hunter G, there hasn’t been any announcement of n3ds exclusive games (not that I know of, at least.) the only exclusive game so far is… xenoblades, xeno… something. The game Shucks comes from.
I’d say yes, buy one. if you don’t wanna spend money on a n3ds, then buy a 2ds or an old 3ds to play a few games. It’s up to you, really.