Probably, but not necessarily. The world changes with time and if OSM contributions languish, it falls out of date with the world and tangibly becomes a worse product. Certainly not inevitable, but a possibility worth noting.
It would be nice to determine some random controls points and compare lag on different mapping service. The average lag would maybe maybe drop under a year for some (and it will depend on which feature, road update faster than building if you account for gps data).
However I really don't see why OSM would necessarily lag more than Google Map or any commercial database. Because the more OSM usage is widespread (directly or through apps) the more human "field sensors" you get to update the map. Same way that I don't think many commercial encyclopedia can claim that they are more up-to-date than Wikipedia to record new facts.