There's a very interesting article by Langlands called Where stands functoriality today which describes some general number-theoretic things from Langlands' point of view as of 1990s or something.

But if somebody was to write an overview of the current state of the subject, what would it say?

Robert Langlands is famous in number theory for making famous and deep conjectures about very abstract things called automorphic forms, somewhere in the 60s.

There's a very interesting article by Langlands called Where stands functoriality today which describes the development of the subject from Langlands' point of view as of 1990s.

But if somebody was to write an overview of the current state of Langlands functoriality, what would it say?