If by "close to 50%", you mean 34%, then sure.
Are you talking about market share in what is sold each quarter or are you talking about what is being used every day? I know that the average iPhone sold in the U.S. gets used for a longer period of time than the average Android phone. And I would not be surprised if the average life of an iPhone is 4 years (two years with the first owner and then handed down or sold into secondary market and continued to be used) while very few people are using four year old android phones. Sure the top of the line Galaxy phones might last four years. But the Android market is filled with tons of cheap phones. Those $300 Androids aren't used for four years. So I'm talking about the addressable market of iPhone users. And I suspect current used iPhones make up much closer to 50% of all daily used smartphones in the U.S.