Guys what if we are simply underestimating the Chinese, What if they have a reusable triple 10m rocket in mind? They could leverage the sidebooster tech from 921 and reusable tech from private companies, hell what if it has four 10m side boosters instead of just 2 we are looking at 500t LEO Payload capacity with at least ~$3,000 per kg (Falcon 9) if not cheaper price tag
Sorry I have to pour cold water here.
921's core and boosters are all 5m in diameter with YF-100K engine, there is nothing from it can be used for your suggested 10m rocket (CZ-9) with YF-130, reusable or not.
There is nothing any "private" company can contribute for reusability either. The fact is that CASC is the only entity in China that has an active ongoing development of reusable rockets namely CZ-8R, and probably another one CZ-6X.
"Private" companies in China are developing their first liquid fueled engines right now compared with mature engines in possession by CASC.
To be clear, there is no CASC (SOE) equivalent in the US. All american rockets are made by private companies with NASA (state institution) involved in early research and coordination. All US rocket companies are private whose engineers are all members of NASA's various programs. On the other hand, China's "private" companies have access to resigned CASC engineers only but no possession of CASC's R&D outcomes. So don't expect them to do as great as their US counterparts.
500t LEO without a revolutionary new technology yet to be developed is a fantasy, be it fantasy by Elon Musk or anybody else. Certainly CASC has no plan of it in their road map.