Can self-publishing co-exist with traditional publishing?

Uta Hagen's Example:

Respect for Acting (amazon link here) -- published Wiley 1973; 2 edition 2008

A Challenge for the Actor (amazon link here) -- published Charles Scribner's Sons, 1991

The Studio Story (Apple Books/iTunes link here) -- published HB Studio mimeograph machine, 1998; Champlain Arts 2019

Beyond books: 

HB Studio (link here) founded 1945

Website: 1998/2018

DVD: Uta Hagen's Acting Class --- Applause Books, published 2004 (link here)