I'm excited for the Karelia/Leningrad map. It started as a custom terrain of Finland by the same Finnish players that made the amazing Finland map for AH2. Now they are turning it over to the IL-2 team to make the Russian portion of the map once they finish Finland.
I just wish it wasn't getting lumped into the Odessa map module and splitting the 8 new planes between them, which seems half-assed. Also, the new planes are variants of existing planes or at least reusing some elements of existing planes, which is definitely half-assed.
The Finnish AF specific planes will have to be done by 3rd party developers. So far, only the Fiat G.50 has been shown in progress.
There's a whole thread on their forum about the development of the Karelia/Leningrad map:
https://forum.il2sturmovik.com/topic/86638-karelia-map-discussion/#comment-1296303