Although sonically his music has changed dramatically, he still has an impact on the African continent. As evidenced by his recent tune with Diamond. And previously his own solo hits like selfie, etc... That alone is reason enough to continue (in his mind).
Someone mentioned it: money. Seems like money is still pouring in, he's now active in Europe, so life is good.
Frankly, there's no age limit to making songs. Whether or not people still enjoy your songs is another thing. I will say though that he's entertaining as an artist/individual. "vieux a lingi ko Kola te" lol