To me, that implies the possibility of there being a "wage ceiling" for people of a given skill level as the other western nations appear to be on a trajectory

To me, that implies the possibility of there being a "wage ceiling" for people of a given skill level as the other western nations appear to be on a trajectory that will top out around the same level at which US wages have stagnated. The existence of such a ceiling does make sense given that the distribution of innate ability in a given population is on a bell curve. Even if we assuming a perfect allocation of resources (capital, education, etc), there will eventually be a point at which an individual can be made to be more efficient in performing a task and without groundbreaking advances in technology that drastically change the amount of value an individual can generate at their peak level of efficiency, there will be no economic force acting to increase their wage. There are plenty of inefficiencies in the current American model of resource distribution, hence the continued slow growth of wages as they get worked out over time, but it looks like we may have exhausted all the "easy" problems given the length of time this trend of slow growth has been in effect.