Toyota have reaffirmed their commitment, and probably won't give up until they win.
It's Porsche that's rumored to be considering an exit at the end of this year, despite being committed through the end of next year.
But top-level prototype racing has always been a house of cards, rising and falling, and words of assurance from team principals aren't binding since such decisions are made above by those above their level.
Audi was going to have a 2017 car until they didn't.
Dieselgate may claim Porsche as well.