Re/code has an article on how Android is Starting to Pull Past iOS in Generating Revenue for App Developers. I suppose it was inevitable that the large number of Android users would eventually tip the balance in terms of traffic and revenue share.
However, I expect some companies will continue to go iOS first. Why? Well, company strategy is often driven by familiarity rather than logic. Many company owners and their designers use iPhones and this will continue to influence mobile strategy. I am still seeing this in designs I receive in that they all too often include iOS idioms.