The reason Flair was able to use that gimmick and get away with it is because many fans of his generation didn't even know Buddy Rogers. Plus, Rogers 'passed the torch' to Flair to use the gimmick. Kind of like when Jerry Lawler beat Jackie Fargo for 'King of Memphis' wrestling. Flair actually earned the right and got the blessing to use the gimmick from Rogers.
Right now, I don't see ANYONE getting a blessing from Flair to be the 'Nature Boy'. Buddy Landell attempted to use it during Flair's prime, but he never was over with anyone. It would simply never work in today's wrestling world, because this world only wants one Nature Boy, and that's Ric Flair.
The days of reusing old gimmicks are over with. Vince McMahon is all about originality, even though the original stuff he comes up with sucks sometimes. The Nature Boy gimmick retired with Flair. WOOOOOOOOOOOO!