Je ne sais ce que tu vas devenir.

English Translation

I don’t know what will become of you.

The translation was a little different than what I expected, so I looked it up. Here is one translation in the Larousse dictionary:

  1. [avoir tel sort]
    et moi, qu’est-ce que je vais devenir ? = what’s to become of me?
    © Larousse 2014