Since "In" is not required, it won't be an issue as long as you are staying in airspace that does not require ADS-B "Out". If you are flying your aircraft in airspace that requires "Out" and you have a non-compliant system, I believe you will get a notification.
What I don't know is what they plan to do about an aircraft that is avoiding the "Out" required airspace's, but has a functioning, non-compliant "Out" system. Will it matter to the FAA whether the system is compliant or not since the aircraft is staying away from airspace that requires ADS-B "Out"?
I don't know that answer so I have sent an email to the ADS-B folks at the FAA. I will post the answer when I get a reply from them.