I have a friend that has been clean for 25 years and her husband has been clean for 30 so yes it is possible.. I do want to add though that this couple, eats, sleeps and breaths recovery.. they are still very active in AA and do a lot of service work.. I think that is part of the reason that they are so successful..
I also have a friend that has been clean from crack and meth for close to 25 years.. he says that he cant be around that stuff at all because the cravings become so severe that his nose just starts running.. to my knowledge he has never worked a 12 step program.. he just decided that he was sick and tired of being sick and tired..