No one knows, but it is very likely as it seems to be some sort of change of series, possibly from Exhibition to FIA or something else, and hence you will be able to if so.
You can't change for each season, but you could change inbetween the Test Seasons, which were tests. You can also change inbetween a change in what the series is, for example you could change inbetween the official FIA Seasons and the Exhibition Seasons, but not inbetween each Exhibition Season.
I'm sure when I signed for Audi I was imprisoned for the rest of 2018. In theory whatever season comes next (test or competitive) should allow us to sign with somebody else.