C5 size transport are for time sensitive, urgent shipment of over-size cargo. It fits in well within US strategic airlift requirements as they are operating in locatins all over the globe. More specifically urgent airlifts from US continent to Europe, or to Israel and Western Pacific region to expedite deployment of heavy equipment for US intervention forces and its allies.
The Ukranian/Russian heavy lifters are used mostly on civilian commercial shipment instead of military cargo.
If China were to proceed ahead with developing a large heavy transport of the same league. They should consider who will be the main end user of these aircraft.
In military these heavy lifters come handy for fast deployment of heavy artillery, air defense battalion, heavy engineering equipment etc to Himalaya region, to quickly change the balance of forces against the opponent. However, if PLA has pre-positioned their equipment and resouces at nearby regions that required only half a day to one day of travel by road to Tibet or any potential hot spot. The priority for heavy lifters would be lowered.
Commercial shipment of over-size equipment are mostly non time sensitive as the maritime shipment dates can be arranged in accordance to project schedules in that the timeline of delivery would have been fixed years or months before. Unless the sea route has been blocked or endangered like current Red Sea situation.
Thus C5 size heavy lifters are nice to have, but not a neccesity, since China has no global defense obligations. However, there is a niche market in transportation of space rockets and fuselage of large aircraft like C919, C929 and may be a larger C9X9 of future.
