Definitely a Blade Runner gun as a homage to that iconic movie (Fallout 1&2 had those).
I really like the mecha design from GitS the original manga and SAC TV series. Design is sleek, super functional and simply genius: bull-pup designs, angled magazines with crazy capacity, loads of accessories and very "realistic", industrial look of the future. CDPRed know all this so i bet we'll see weapons like that popping up in the game.
On the side note, as we're seeing today, consumer electronics tend to go towards multi-functionality in one box (smartphones) the same can be seen done with personal weapons. Nowadays, in many NATO armies looking for new infantry basic armaments, arms companies enter competition with weapon systems not individual models. Just look at a G36 frame (i know, pretty old now but a good example). Can be configured into a basic infantry man weapon, or with just a few accessories into an LMG or a shortened SMG size CQB variant. GitS mecha designers have done the same years before with the Seburo frame, with Kusanagi using SMG, assault or spec-ops variants.
Edgerunners i ran with or ran them in the old PnP games originally went for a pistol, SMG or shotgun and assault rifle quickly realizing that that look made them Hedgerunners rather than street warriors of the 21st century, with all kinds of different ammo stuffed in their pockets or pouches and barrels sticking out not to mention the weight and clatter. Machine pistols and short and sweet SMGs using the same ammo became standard for everyone on my team, with a supplement of an assault rifle for Solos with a grenade launcher/shotgun underslung modules.