Name me a "large object" that the PLA would urgently require in a conflict or humanitarian aid.Another poster has mentioned Semi-retractable landing gears.
PROC need such a plane for & of it's own...transporting large object that don't fit inside Y-20.
Xi Jinping's military reforms in 2015 were structured not only on modernization, but more importantly how newly modernized equipment can best serve the needs of the PLA. In essence existing Y-20s and amphibious ships need to be able to effectively transport existing infantry troops as well as armored/mechanized/artillery equipment to respond to any sort of military or humanitarian event within short notice - case and point a Y-20 can fit two Type 15 tanks, and so 2x Y-20s are able to bring an armored platoon (if my understanding of PLA doctrine is right, a PLAAF Y-20 Transport Regiment would therefore be able to airlift an armored company of ~14 tanks) to the frontlines. That's more than enough firepower on the battleground until heavier Type 96/99 MBTs and weaponry arrive from the LPD/LHDs. Future projects also have to be designed where they fit into established doctrine and are aligned with the 2015 military reforms.
Even in a humanitarian aid mission, such a large aircraft would struggle to find a suitable airfield that has a long enough runway to land on as well as strong enough taxiways to maneuver around. I also highly doubt it would be physically possible to land on unprepared (dirt) surfaces - I'm struggling to see the practicality of it.
There won't be many "large objects" that would require flying around, and alas the aircraft you're proposing would struggle for flying time. A plane needs to be flown every now and then in order to keep the parts moving or else you risk stuff breaking between long-periods of idle (and why commercial airlines are losing money during the pandemic when the majority of their planes are grounded), and so you'd be forced to fly such a massive and fuel guzzling aircraft just for the sake of it... That really amounts to an utter waste of resources.
Because the market you're describing is extremely limited, Antonov and Atlas Air practically have a monopoly on it with their specialized fleets of An-124s and 747 Dreamlifters. It's hard enough for COMAC to crack into the Airbus+Boeing commercial aviation monopoly, there really isn't a gap at all in the specialized cargo/freight charter market for an aircraft manufacturer in China to cut into.Why charter when you have the tech, expertise plus capital to build one yourself.