Japan’s Softbank, and its maverick chairman Masayoshi Son, has been interested in adding a US cableco to its growing wireless empire for some time, either to combine with its existing US subsidiary, Sprint, or to replace it. There have been various reports over the past year, of talks with major cable operators as well as T-Mobile USA and Dish Network. Now, the reports are concentrated on a possible $100bn bid for the second largest cableco, Charter. The aim, it seems, would be to create a fixed/mobile giant to compete with Verizon and AT&T. Sprint’s years of problems have been alleviated somewhat by Softbank’s financing of its ambitious densification and 5G plans, which should finally see it turning its much-vaunted 2.5…