I wouldn't hesitate to buy another Obi20X, I don't see any risk.
Even if they discontinue the series tomorrow and come out with new ones, I cannot see google changing the service in any big ways now that the new connections are up and running. So, even if they are discontinued, they aleady work with the new GV service,and I suspect they will for a long time. You don't go to that much trouble to make it work if you are going to flush it 6 months later.