[necovek]

Obviously, Matt believes this or he wouldn't dedicate to a start-up in the field.

That does not make it true or likely.

As a counter point, since he believes code review is not going away, how is one going to become a great code reviewer?

My answer is by learning to be a good programmer and asking good questions. Code review is a discussion between two or more people with awareness of context, goals and reasons behind the code as is: it's a collaboration.

But reviewing unknown code by unknown author requires such a tremendeous amount of work (and notably focus and concentration): that is so much harder without an ability to ask questions about reasons for each specific area of the code.