... K/R were preparing all season to move into seniors. But I reckon that they could return for junior worlds (with the age adjustment)
Also C/Y and RB/H age out of junior ice dance.
But Cesanek/Yehorov also have the option of staying junior internationally, for the same reason that you already referenced for Kazakova/Reviya (the ISU extension allowing 2019-20 junior dancers to stay junior an extra year).
afaik, C/Y have said nothing either way re junior or senior for 2020-21.
(They also could stay junior domestically, as USFS does not have age maximums for junior.)
ETA:
The option to stay junior would have applied also to (Rose) Brown/Hernandez (if they are who you mean?), but I see that they are committed to moving up to senior.
https://www.facebook.com/permalink.php?story_fbid=1386050484917831 (Jun 25)
Hmm, as it says upper age limits I thought it just applied to the male ice dancers. I got the info from the 20-21 skating season on wiki, where it says junior males in ice dance: Born between July 1, 1998 and June 30, 2007
... I agree with you about the foolproofness.
Maybe it does indeed refer to both. I've edited my earlier post to include the doubts I now have ...
... Anyway, I'm quite excited to see how the programs will be updated if couples do choose to stay junior. Junior Ice Dance is one of my favourite categories!
What about Nastya Tarakanova? She is 16 years old. Russia wouldn't put her on the JGP.