all this flaunting in public leads me to believe this is indeed primarely aimed at export. of course possible sales wont start for another 6-7 years, since the thing hasnt even flown yet, but it is a way of creating a buzz. i dont know of a single example of a fighter plane made with one piece wing/fuselage. The wings were left on the plane on purpose, so everyone would know what was underneath - a new plane. It would be much simpler to take wings off and load the whole thing into a box, cargo plane, etc.
Secondly, i dont think any air force nowadays has room for a hi-med-lo mix. indians are doing it for now, but theyve got a bunch of older planes to take care of first before creating a proper hi-lo-mix.
Thirdly, hi-lo mix made out of just j20 and this mystery plane, lets call it j21, again doesnt make much sense as the low bit is still too expensive. SSSR tried it in 80s with su27 and mig29 and, frankly, that wasnt such a good idea. Both the ruaf and mig bureau would have had it much better if mig29 was a slightly smaller, single engined plane.
Only good spot for this new plane would be on the carriers. And for that it just doesnt make too much sense to invest in j15 only to have it superseded by j21 not even 10 years later. I dont think china will be so much wasteful (it wasnt before) to construct a new plane, produce 50 airframes, train the ground crews and pilots and make infrastructure for it, and then double all that effort with another brand new type of plane within a decade.
btw, that top down pic show how large wings are. my rough measurements say around 10.5 meter wingspan, but maybe someone can try to do a more precise assesment.