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There was a hint of this on the Blackmagic Forum, but just speculation. The concept expressed there is they need to go to a mirrorless mount to have access to more lenses, and L-mount might do that, especially with all the adapted lenses.
I am a fan of Blackmagic, and always wanted a Mini Pro 12K, but never had a project that would justify it. But if they made a full frame L-mount version, and I already had all the lenses it would be more tempting.
DJI is part of the L-mount alliance, but we never see them on this forum. I don't know what other photo camera companies might be candidates.