Historically it would be wrong for the present time period, but we may see it when the new theatre is released with the next TF patch, or soon thereafter.
The aircraft in ClOD are so much more complicated than in Il2 1946 that even a "small" weapons mod, like adding cannon, is no small thing.
In any case a cannon armed Spitfire will probably come first, possibly with the teething problems that were experienced historically.