This is fantastic news. I am now very hopeful for the future!
In terms of DLC content, (I assume you won't tell us yet but

) what kind of DLC are you looking/wishing to release? I would of course love to see more flavor packs and especially adding unique mechanics and such to certain nations/cultures/religions to differentiate them more in playthroughs, rather than just modifiers.
I would also love to see DLC expansions more akin to EU4 and HOI4, adding hosts of new features and mechanics.
Another cool thing would be DLCs that add additional start dates, Classical Greece, Alexander, Caesar with Gallic and Civil war, Triumvirate and Roman Empire, Christianity etc. With maybe unique mechanics for those starts. A later start would also extend the timeline for all previous dates and if there is something like an Attila DLC for CK3 you could have a converter from Imperator to CK3.