I think Chinese/Cantonese/Mandarin will be an important one(s) definitely!If the human race can stay peaceful, China will probably begin to dominate the world economically, especially since they are buying up real estate all over the world to mine resources etc. (especially in Africa). This is a scary thought though, because the vast and hungry machine that is China has a big appetite and there are a lot of worrying things going on in China right now.
That aside, Chinese foreign nationals are in every country and they have a beautiful traditional culture. I think it is safe to assume there will be more spread throughout the world in the near future, leading to more cities like Vancouver with high "Asian" populations.
Chinese/Mandarin/Cantonese is very hard to learn though, the complex alphabet and wording further complicates an already complex speaking language system, therefore I put my bets on Esperanto being the language of the future. Young learners in the UK and other countries already learn it in school and they have had spectacular results in cognitive and learning skills (not only in Languages, but in maths as well!). Esperanto is also very easy to learn and it is offered on various apps and platforms - it is also a subtitle option on Youtube!