What do you guys think, do you think we will see more consoles get added to the service after GB & GBA or do you think Nintendo is pretty much done adding anymore consoles on NSO.

Many people are desperate for GameCube games to eventually come to the service, including me. However, im starting to lose hope on that since Nintendo unfortunately has largely ignored adding GameCube games to the virtual console in the past and based on how slow Nintendo been with the NSO service in comparison to prior years with the virtual console, it seems even less likely then before they'd bring it out now especially this late in the Switch's lifecycle.

However, more importantly I feel like Nintendo wouldn't want to put GameCube on NSO cause they'd rather resell GC games at a higher retail price then just add it to the service for a smaller profit. GC games are new and relatively modern enough for Nintendo to justifiably re-release them without needing to remake the entire game to make it look new and a game worth a retail price, all Nintendo could do with GC games is upscale them and they'd still look pretty modern, we've seen it with TP HD on Wii U. We already saw Prime remastered, to be fair though the Prime remaster was definitely an amazing remaster that was worth the price.

DS games might be more feasible, we saw it on Wii U VC its probably easier to emulate and I dont think DS games are modern enough to be able to be resold and remastered as standalone games. The dual screen might be difficult to implement on Switch however unlike the Wii U which was already asymmetrical like the DS.

The Wii & 3DS I'd also feel like Nintendo would rather just resell and remaster those games at retail than put it on the service, we've already seen Skyward Sword do this.

I would imagine they will carry over the service in some form to their next system after how much time they have spent building it up, very possibly with a name change, and in that case I fully expect more systems will be added at some point, if only a couple.
As for whether there will be added more systems within the lifespan of the Switch, I doubt it though, particularly since the GB and GBA started out with so few games, it'll take them quite a while to really build up those libraries.

On the Switch probably not unless they release the rumoured MP2/MP3 ports as NSO titles, but I think they will charge for them if they're real. On future consoles they definitely will.

Yeah DS could still be possible. I don't think GameCube (and Wii even moreso) is happening. Those games are also much bigger, storage-wise. The Wii also had things like TurboGrafx-16, NeoGeo and more SEGA systems, that can still happen.

I voted no but that really just applies to current Switch. They should wait for a successor before adding more.

Besides the obvious ask of GameCube, I’d like to see Dreamcast added at some point.

I voted for no. GameCube is most likely too big of a console storage wise to put on NSO. At least at the current price point.

If there would be any additional consoles, I would guess Saturn or Dreamcast to go along with Genesis.

Gamecube should get added at some point since it would for sure cause a notable boost to expansion pack users. Assuming NSO gets carried over to the successor that would be a good time for it. And Sega could let another system get added.

That's all the Nintendo systems I expected on NSO, plus Genesis which I didn't expect.

I don't really think we'll see more non-Nintendo systems just cuz Nintendo will have to share their NSO subscription revenue with other companies then (same reason we don't see many third party games). But its not impossible we'll eventually see Dreamcast or something on there.

GC is a possibility but if it comes to NSO I don't think it'll get added until next-gen. It would be cool to get GC but I don't expect it, and mostly at this point I just want an Eternal Darkness remaster, Zelda WW, Prime 2 (which we expect to get on Switch), and just new entries in some series we haven't seen since GC rather than playing the old games. But it would certainly be awesome if they did add GC to NSO eventually. Though many of the best games on GC were actually third party (a rarity post-SNES) so GC on NSO would miss much of what made the system great. And if we end up getting ports/remasters of both Prime games, Z:WW, Z:TP, and we got Sunshine on 3D All-Stars, it definitely lessens the impact of a first-party GC library on NSO.

I think we're done getting new systems for NSO this gen at least. But maybe we'll see one or two more added to the service in the first two or three years of next-gen, but I don't expect it so it'd just be a nice surprise. DS and 3DS are a no go because they require double screens. At this point I just want them to get the N64, Genesis, GB, and GBA libraries built out so by the time next-gen launches we'll have the full libraries that Nintendo planned for all these systems on day one for Switch 2.

Only if they actually carry over the games to the next system, which I don't think will happen.
Nintendo's interest in providing legacy content to their player base is so low that it's somewhat surprising that Genesis, GB/GBC, and GBA games were added. NES, SNES, and N64 seemed like a given from pretty early on.
GameCube and Wii games are recent and "modern" enough that Nintendo would likely rather port, remaster, or remake them than allow us subscription access to them.
I don't see any GameCube or Wii games coming to the Switch unless they are sold on the eShop (like I just mentioned). I could easily see Nintendo charging $20-$30 for ports of GameCube and Wii games, and they've shown $40-$60 is their desired price for remasters and occasional remakes.
Switch 2 (or whatever the next platform is) may have GameCube and Wii games added as part of a subscription, but I'm not counting on it.
Interesting enough, the most likely platform that could be added to Switch (but probably won't) is the PC Engine/TurboGrafx-16.