Possibilities I can see:
- Retained by McLaren (if they have any sense and want to have a shot at WCC)
- In the event of 3-car teams, maybe McLaren, Ferrari or Red Bull (surely RB won't want to have 2 inexperienced drivers alongside one not very experienced driver?)
- WEC team (Toyota or Porsche)
He's clearly not ready to leave F1, so he'll only go to WEC if he has no good F1 options.
Hopefully in Abu Dhabi, he'll get another chance to remind people how good he is.