Maybe its me, but Duchovny would have been a disaster as Mr. White. Too good looking for a for a science guy, and generally played "soft spoken" characters. I definitely could see Broderick playing Walt.

Breaking Bad (2008)

Sony and AMC were initially reluctant to cast Bryan Cranston because of his previous comedic roles. They approached John Cusack and Matthew Broderick for the role of Walter White. When they both declined, Vince Gilligan was able to cast Cranston. However, the rumor of John Cusack being offered the role of Walter has been debunked by Cusack himself in a 2020 Guardian interview, when he claimed no such offer ever came through his agents, and even asked Gilligan himself who denied making a formal offer for the role.

https://www.imdb.com/title/tt0903747/trivia?item=tr1744534