Whether Airbnb will reinstate or replace its sign-up offer scheme is unknown. Although referral programs are a terrific way for businesses to get new clients, they aren't the most successful long-term tactic. In order to attract new clients, Airbnb has to bite the bullet on both ends (paying referrers and suffering losses on new users). Since Airbnb is a significant player in the travel sector right now (mass adoption, public listing), they might not believe that sign-up offers are the most effective growth strategy right now.