shouldn't the "San Gabriel Mountains," name be unofficially be retired and a new unofficial name like "The Baldies" or "Baldy Country" takes its place

The name "San Gabriel Mountains" is well-established and recognized for its geographical, cultural, and historical significance. While informal names like "The Baldies" or "Baldy Country" might be used by locals or avid hikers to refer to specific areas within the range, it’s unlikely that the official name would be changed or retired. Retiring a name typically involves significant historical or cultural reasons, and while the idea of using a more localized or informal name may appeal to some, the established name generally retains its importance in maps, signage, and official references. Ultimately, names often evolve through community usage, so informal names can coexist alongside official ones without the need for an official change.