I am asking myself the same question. The thing is that China in the future (and probably already) plays 2 roles in teh contemporary industry and market.
a. almost everything is built there.
b. it’s one of the biggest (and maybe it will become the biggest) market.
so, in one way or another almost any industry is dependent from China and therefore i would think that if a designer (not Chinese) could speak Chinese in the future (the very near one) will have a competitive advantage.
about a year ago i was in Hong Kong (in HK people do speak english so no major problem) + China and last January i was in Japan. i really loved Japan and i would really consider to move there and work at least for some years. An interesting difference i found was thet wesetrns in HK were were NOT speaking Cantonese or Mandarin but it were the locals who had to speak english. In contrast, in Japan it were the wesetrns who would speak Japanese. If you want to survive in Japan you HAVE to speak Japanese…so… how about learning both Chinese and Japanese …