Green is an RFA next season (under current CBA rules), and has a great comparable in Marvin Willians:
Both 24 years old, PER around 13, mid-teans in scoring, 5-6 rebounds, decent shooters, good defensive potential...
I can see Green signing a 4 year $27 million contract if a similar CBA is in place next season. That is a little less than Williams got, but Williams was a starter.