However, if the cadet program becomes the only route for second officers to join the company, in enough time, without direct entry or icadets, nearly every pilot for Cx will be a HK local.
I don't think that will happen - if the entire concept of icadets is cancelled, the pilot recruitment framework of the past would reappear, with an ab initio cadet scheme for locals and a DESO program targetting expats. Regardless of English or lack of background/educational diversification, it would be impossible to rely solely on HKG for new pilots because there simply are not enough people who are interested and have the necessary aptitude or skills. If that wasn't true then local pilots would have begun to dominate the Cathay pilot ranks, just like other airlines in the world that set up cadet programs for its nationals.