Since we're talking about high-supersonic if not hypersonic aircraft (honestly I'd prefer the latter to be the case) that is capable of taking-off and landing with its own propulsion - This would mean operational altitudes ranging from 20 to 40 kilometers (or ~66000 to ~131000 feet) with TBCC engines.
In this regard, strategic ISTAR would be a good start, where the advantages of extreme high speeds and altitudes relative to the Malan WZ-X means the ability to quickly transit to areas of interests, especially when dealing with time-sensitive and objective-critical missions and/or targets, alongside the ability to better evade interception efforts than its mid-subsonic counterparts.
From there, we could advance further into having shallow IWBs for intercepting enemy airborne assets at ultra-long-range distances using ULRAAMs with (largely) ballistic trajectories. Moreover, if the ULRAAMs have certain hypersonic gliding capabilities, the effective interception ranges could be expanded even further.
There could also be the potential with ASAT capabilities, though I caution against going any further than that, especially considering the immense degree of complexity, challenges and costs of which such platforms' procurement and operation would entail.
