Boeing seems to have come up with the early details of its own design for a hypersonic tech demonstrator that would be a spiritual successor to the SR-71 Blackbird. This means that this is meant to be a logical extension of the company's X-51A Waverider: the wedge-shaped, twin-tail body is designed to minimize drag while gulping in as much air as possible. With features of the new model being about as long as the Blackbird, its Mach 5-plus top speed would definitely supersede Mach 3.2 jet.
The progress on the design depends on if the American officials select it for development (or not) under both DARPA's Advanced Full Range Engine program and the US Air Force's Turbine-Based Combined Cycle study. And if by chance, it fails to go ahead, it'll be a while before a production aircraft comes up.
Boeing is expected to start by making a single-engine proof of concept vehicle and would move on to a full-sized, dual-engine version. Boeing's Kevin Bowcutt reportedly told Aerospace Daily that the design is still evolving, so this is more a reflection of the current state of affairs than anything.
