7th gen aircraft research is probably only in the preliminary stages right now. China and the US would be the ONLY nations right now even remotely looking into it, so I don't know if we can reliably speculate what 7th gen might even entail since we haven't even properly defined 6th gen yet and even great European powers don't even have their own 5th gen fighters yet
We can look at the Nantianmen project for a glimpse of what the future 7th gen might be though there is no any definition for the 7th gen at this moment.
Although Nantianmen is not a real project but its intention is to inspire the imagination of kids who would be the aeronautical engineers/designers when they graduated from universities 5 to 10 years from now. And they might bring new out of box ideas to the current aircraft design teams.
IMO advanced AI and supercomputer level computational power and powerful engines for near space/ orbital super or hyper cruise and inter-operational switch between human and machine autonomous decision making and flight control should be expected.
What is also not mentioned earlier about this arrow tip aircraft is that it can simply be the other end of the spectrum for "6th generation fighter".
While J-36 and J-50 focus their leap in all aspect next generation stealth while improving every other parameter except
maybe agility, they've left room for a stealthy, high supersonic aircraft. It's no secret that China's performed payload dropping flight tests from HGV and/or FOBS and has some disclosed (public efforts) academic efforts at pursuing Mach 4 payload separation aerodynamics. Since China tested payload separation from Mach 20 + HGV back in 2021/22, this public paper on Mach 4 payload separation is nothing to write home about (for China at least).
If flying so fast makes you a little to a lot less stealthy, in no small part due to the shaping and aerodynamics required for such high supersonic flights disagreeing with the best stealth geometries (pure flying wing - subsonic). At least this entirely yet unexplored domain of "next generation" air to air mission focused aircraft still needs exploring! China has all the excess engineering, industrial, academic overcapacity to explore. What's to say that the generation 3 thinking of missile energy doesn't now actually trump the generation 4 thinking of balancing BVR and WVR capabilities while noting that BVR actually does require a lot of kinematic talent for a fighter to excel.
Not only does this hypothetical aircraft have legs as a "fighter" but also recce/ ISR, comms, sensor node, strike aircraft/ small bomber, it even presents as a technology demonstrator. One day, you still need to fly faster. Every step in improving and achieving a future product is made by these steps.
7th gen will be defined by propulsion if 6th gen intend to make use of VCE, 7th gen may use combined cycle to expand the envelope of operating theatres, speeds, altitudes. Enhanced sensors as we'd expect, perhaps embedding sensors into the skin or activating the skin in whatever form future (today's experimental) technology allows. Revolutionary sensor types, moving away from our current emitter - receiver physics (perhaps finally making use of quantum entanglement as with the "photonics radars"), much more adaptable airframes and 6th gen (at least with J-36) has already shown with hingeless/ covered, moving control surfaces.
MUM-T is a given, boring and separate to these discussions. It's far from the leading edge now and both China and US have been actively fielding MUM-T for some time with the latest pairings done by J-20S and the US with the Ghost Bat simply being a new generation. Russia has done MUM-T with S-70 Okhotnik and China and US have long since used some form of MUM-T just much less sexy and visible compared to GJ-11 and J-20S of today's or perhaps even the UADFs with J-20S.
