It is hard to imagine what cards they will add to support Green-Blue because those were the 'greedy carry' colors. Though the Red-Blue synergy worked pretty well, that mostly came off the back of the Face already splashing the support spells half the time and the fact that weirdly face cards benefit from you having fewer red cards quite a lot of the time (though they added some nice cards that actually reward Skill cards in High Caliber Ops), so the Social Adept just was a natural replacement for the face. And the rigger didn't work well at all, hacking is, again, notoriously greedy and while many of the hacking-Combat cards were good none rewarded you that much for having both hacking and combat.
I suspect that Technos will bring weird combo cards. Blue and Green both had this (Green loved to recur things, blue liked to play big spikes of damage, so big spikes of damage that require finaggling your deck feels appropriate and weird) and any hypothetical resonance card that helps your consistency would also be playable with the 'base' roles, which is important.
It is also interesting to think about what the hypothetical Black-Red role would be. Infiltrator perhaps? Assassin? Faces often grabbed Samurai cards (And vice versa to a lesser extent, a pleasing symmetry to the tabletop) and faces have native support for going 'off color' anyway, but the main overlap between Black and Red is healing and damage negation, so... combat medic maybe? It is pretty easy to imagine the mechanics and some of the thematic for black-red, though not for the entire class: Taunting, 'grace under fire' healing, rallying teammates to draw cards (though that all intrudes a bit on Heart of the Team). Maybe Black-Red will focus on Red's economic aspects? A bounty hunter perhaps? That would fit both facework and killing folks, and cards that increase teamwide cashflow while also hurting the enemy would be extremely welcome in Crossfire, as the glacial pace of deckbuilding is what made so many of my friends bounce off it.
My main hope is for them not to print cards that have their low cash payout as an element of how powerful they are. Yes, technically a hard enemy that is just like a normal enemy but pays basically nothing makes the game harder, but deckbuilders aren't good when you aren't able to actually build the deck, and its so weird the average normal card is harder to kill but better paying than the average hard card because the hard cards mostly exist to choke your economy till you tap out.
