According to SAIC, this Excelle (凯越) utilizes an all-new global modular architecture, which is likely the VSS-F modular "set" that will generate a large no. of passenger cars of various sizes over the next decade. In particular, the VSS-F B/C platform will provide the base for this car (the derived platforms are alternatively coded as JBXX/JCXX/9BXX/9CXX for B- and C-segment cars). Going by a list published by market analysts IHS Markit, the new Excelle is designated 9BLB.
Learn more on the VSS-F architecture here.
Thus, the Excelle is not related to the Cavalier or any other prior vehicle. Interestingly, studying the IHS list, it is also evident that the Cavalier (K216), new Excelle GX (K221), and by extension, new Excelle GT (K215/K211) are based on a Global Gamma platform (either Gamma II or G2XX) and not on the Delta II platform (Cruze Classic, old Excelle GT, Excelle XT, old Buick Verano) as everyone believed.
Yes, it is true because the GM-planned future Corsa was to be based on 9BXX. The stillborn Corsa F hatchback was 9BJO, so presumably the sedan version would have been 9BSO. The next Buick Encore will be 9BUB and the next Chevrolet Trax, 9BUC; so if there had been a future Mokka X, that too would have been 9BUO.