Have read the migration guide, and kind of read this “if possible, and falls back to timestamp" = will work.
This config-change, will it work in the long run (incubating)?
I can understand the asking for trouble, problem here is our database is already there, and it worked in hibernate 5.x

So what do you suggest we should do in this case, to be future proof?
Change database?
Change datatype in entity?
use the config: hibernate.type.preferred_instant_jdbc_type