Watching Pestily's podcast with Nikita (head Dev @ BSG) some awesome information revealed.

As above biggest patch 12.6 to have some huge changes. (Edit: Nikita has since confirmed customs addition won't be until 12.7)

Other interesting info. 12.5 patch (next patch) NVIDIA filters will be banned as colour and brightness post FX filters are being added in game menu

12.7 is when Vector SMG is expected.

The next map release will be either streets of Tarkov or lighthouse as both sound to be in similar development stage. No time frame or patch number given.

(Edit: Nikita has since confirmed customs addition won't be until 12.7)