That is pretty much how I think of dated names vs. classic names as well. Even if a name isn't nearly as popular as it used to be, I usually still see it as classic if it was well-known and regularly used prior to and after its heyday.
Laura, Mary, and Rebecca are names that seem like classics to me even though they aren't as popular as they once were.
"Dated" names that come to mind:
Brittany - I think of the 1980s-1990s.
Tiffany - 1970s-1980s.
Karen - I think of the 1940s-1960s in particular.
Sharon - Mostly the 1940s-1960s, but it seems somewhat early 1970s to me too.
Brenda - 1950s and 1960s.
Kathy / Cathy - Katherine is a classic, though.
Carol - I automatically think of the 1930s-1950s.
Donna - 1930s-1960s.
Lindsay - 1980s-1990s.
Diana is a name that is on the cusp of dated and borderline in my mind. I think of the 1940s-1960s when I hear it, but it is still regularly used and has been in regular use for quite some time. Diane definitely seems more dated to me. Aside from a friend with the middle name Diane, I don't know of anyone who was born after the 1960s who is named Diane. I have met people in their twenties named Diana, though.
Dakota, Mackenzie, and McKenna will eventually seem dated. They already strike me as 1990s-early 2000s names.