(FWIW, I'm the technical lead on the Quarto project)

RMarkdown isn't going anywhere! Quarto exists to bring the RMarkdown experience that folks love to a broader set of users and contexts. It is true that we try to keep the .qmd experience in Quarto pretty close to the .rmd experience in RMarkdown, and it is true that Quarto does things that RMarkdown never will. But it's not the case that "RMarkdown is being phased out and replaced with Quarto".

Thanks for the correction!

I might be conflating rmarkdown with knitr because the developer of knitr (who was employed on some capacity by Posit) was let go.

For how long do you think Posit will continue to support both platforms?