I don't know about you guys but I've always been a believer regardless of whether or not the DMCA is indicative of anything. So, I think there's only one big talking point for third kit speculation - Side Order! There are some unique subs and specials that aren't represented in their respective weapon's class yet so I think it's worth talking about.
Dualies - Curling Bomb + Reefslider
Curling Bomb is on Enperries already and if we were to have a third Reefslider on a short-ranged Dualie I think I'd lose my mind. Reefslider is probably meant to both be a parallel to Triple Splashdown and to emulate how the special feels for Dapples Nouveau and Tetras.
Brella - Sprinkler + Ink Storm
Sprinkler is the Splat Brella's vanilla sub but Ink Storm isn't currently on any Brella in this game. It's worth noting that this kit is identical to Splatoon 2's Splat Brella but it wasn't on any other Brella in Splatoon 2. They totally could've chosen to give this thing Triple Inkstrike in Side Order but decided against it. Maybe because nothing else has Ink Storm in this mode? I guess there's not really a better candidate. It's been said before but the healing buff Ink Storm recently got would give it particularly interesting synergy with basically any of the Brellas in this game, although sadly I doubt they'd put it on Undercover because Splattercolor Screen is probably one of the closer specials to it.
Shooter - Splat Bomb + Trizooka / Splat Bomb + Triple Splashdown
Splat Bomb and Trizooka are already both on the Splattershot. Funnily enough Triple Splashdown is the only special usable in Side Order that is not represented on a Shooter. If we get third kits, I would be surprised if Burst Bomb + Triple Splashdown Splattershot weren't one of the first things they'd add both as a reference kit to Splatoon 2 and as an easy avenue for less-experienced players to use a fan favorite special.
Roller - Burst Bomb + Kraken
The most iconic sub and special for two Rollers already, those being Carbon Deco and Krak-On Roller. Nothing to see here.
Charger - Ink Mine + Triple Inkstrike
Ink Mine is already on the E-Liter and Triple Inkstrike is already on Z+F Charger. Once again, not really much to talk about.
Slosher - Suction Bomb + Triple Inkstrike
Triple Inkstrike is already on the vanilla Slosher and Suction Bomb is on the Dread Wringer. There's some chance that they just wanted Splat Bomb to be the Shooters' thing for whatever reason but wanted something that felt similar to Splat Bomb to try and make it feel like the vanilla Slosher's kit in this game. If not then I think Suction Bomb's at least a little bit interesting because there's no upgrade to make a Side Order Slosher have Dread Wringer's double sloshes. Unless I missed something the base Slosher is also the only bucket that was ever given Suction Bomb before Splatoon 3.
Splatling - Splash Wall + Booyah Bomb
This is fairly straightforward as well, but for a different reason. In every single game to this point, the Heavy Splatling has had three kits, and the subweapons on each have been Point Sensor, Sprinkler, and Splash Wall. Giving a third Heavy Splatling Splash Wall would continue this trend. Hydra has Booyah Bomb in this game but the Heavy Splatling Remix also had it in Splatoon 2.
Blaster - Curling Bomb + Wave Breaker
Clash Blaster Neo has Curling Bomb and Range Blaster has Wave Breaker. To me this kit still stands out a little bit because as a package it's not really like anything any Blaster has in Splatoon 3. Still though, not really much to talk about.
Brush - Ink Mine + Ultra Stamp
This kit is completely identical to Inkbrush Nouveau. Next.
Stringer - Toxic Mist + Killer Wail 5.1
Okay this is just the vanilla Tri-Stringer kit. I guess I couldn't really picture either this sub or special on any other weapon here in the context of a Side Order run. Honestly I like it a lot in Side Order but that's beside the point.
Splatana - Fizzy Bomb + Crab Tank
Crab Tank was given to Splatana Stamper Nouveau but Fizzy Bomb is noteworthy. Splatanas in general have a focus of damage combos as a big part of their design and even if those don't really exist in Side Order, there wasn't really another good candidate for Fizzy. It just makes more sense to give the Roller Burst Bomb so this could've been given Fizzy Bomb as a stand-in for the vanilla Stamper's Burst Bomb. I could see any of the three swords getting this if it is meant to be a hint though - Wiper would love a kit that enhances its mobility, Stamper has a lot of room for an interesting third kit in general, and Decavitator is the only one of the three that doesn't have a combo-oriented subweapon even if that might be because its bigger focus is on the one-shot.
Not a whole lot of new stuff here but it is worth bringing the few things there are forward even if there's still no guarantee that third kits are happening. Speculation (and blabbing) is just fun.