[tex-k] [MacTeX] Update TL2020

[Karl Berry]

    However, as the attached screenshot shows, 

No screenshot.

    My question: Is there a way to change $TEXDIR to
    /usr/local/texmf/2020basic 

I can't speak authoritatively to (Mac)BasicTeX, but as far as the
original TL goes, everything is dynamically determined, so that all the
binaries should "just work" wherever the root of the tree is, be it
/usr/local/whatever, /foozler, /I/hate/tex/, etc.

"TEXDIR" only really exists at installation time as a convenience. Thus,
It doesn't seem to me there is any need or use in rerunning the
installer.  mv /usr/local/texmf/{2019,2020}basic should suffice.
Is there a problem with the programs after doing that?

Knowing Dick, I doubt he inserted any new year dependency :). AFAIK
BasicTeX is the native TL install using scheme-small, plus Mac-specific
tools. --best, karl.