1. Stay on the last certified version until everything is certified.
2. Incorporate the parts that can be certified.
They're promising yearly updates. I'm asking what happens when a new upstream feature has already gone uncertified for one full year. Either they blow past the deadline and release nothing for over a year, or they ship what's currently available.
There's no third option. Ferrous doesn't have a time machine, and AdaCore is just explicitly saying that they'll give you what they have at least once a year.