I know that MGM released all DVDs editions of Truffaut's Mississippi Mermaid (zone 1 is poor, there's even various cuts in the footage; zone 2 is not better- I don't remember which I of the 2 is anamorphic but it even looks work in anamorphic (I have both editions).
I can't understand why MGM never put money to release a proper transfer. It's the worst transfer of all the other Truffaut movies by MGM (they are more or less average, but L'Enfant Sauvage ou Adele H. is "ok"). The sad thing is that La Sirene du Mississippi turned out to be my favorite Truffaut...
Now that Last Metro will be released, I was surprised to not find in the bonus a documentary which would explain the connection with La Sirene du Mississippi. How the 2 movies are connected.
To be honest when I saw Last Metro announced on BR, I was really pleased but couldn't help to think "if only this could have been Deneuve on Blu-Ray in Mississippi Mermaid !"

If one day the MGM release is OOP I really hope that Criterion will try to put is hands on Mississippi Mermaid..
Until yet all the Truffaut on Criterion have a MK2 logo at the beginning (being the Antoine Doinel box set, Shoot The Piano Player, etc... Last Metro is also own by MK2 in France). It's odd to notice (I have both released) that Criterion did better in terms of picture quality than the French MK2 Doinel box set.
Last Metro (so La Peau Douce (which would deserve a Blu-Ray transfer

) were both on the criterion forthcoming list since years... Both are released by MK2 in France.
Judging all the MK2 release, perhaps we could hope Les Deux Anglaises et le Continent, Farenheit 451... But some major Truffaut movies are poorly treated by MGM...
Did Jon Mulvaney ever said something about releasing some other Truffaut ?