3 things.
First, I think the question is irrelevant to the underlying question, which is, “where they being disingenuous when they made these features optional?”
Second, there won’t be a 5.5e. Just a cleaned up core set for 5e.
Third, setting aside terminology, stuff like Deft Explorer will still likely be optional, and may not even move to the PHB, since they seem to still want the major expansion books to remain useful after 2024. That the race design will eventually fully replace the 2014 design does not mean that all or even most of the optional rules will do so.