I was going to come on and post this, then I saw an update from Lizzy of Airbnb on this forum in August 2017 (I must've missed it initially) which said they are definitely having one in 2018, but could provide no further details. When I finished reading that, I thought 'hmmmm'. Then, I saw a reply from her with an update in January 2018 saying, essentially, standby that the team is taking this seriously and giving it a lot of thought. C'mon Airbnb, stop toying with us! Airbnb Open is dead.
It's like when an investor tells you to do X, then come back for funding. Or your love interest, says no, thanks, maybe another time. Both of those are the nice way of saying, 'it's not happening.'