After listening to the latest Kongversation about the Rare games on NSO, I would like to put forward my own answer to the constellation theory.
It was brought up that the two horizontal boxes could be either SNES OR N64 games, but see, here's the thing. Between Battlemaniacs, KI, and the DKC trilogy... that's Rare's entire SNES output. Unless they're gonna get the Battletoads/Double Dragon crossover or the Ken Griffey game they made for the system, but I kind of doubt either of those would happen on NSO alone. So my guess is they're N64 games.
I'm agreeing with Hyle that I think we can eliminate Donkey Kong 64 and Diddy Kong Racing from the contenders. It kind of feels like they would be revealed in their own presentations as Donkey Kong games, rather than revealed as Rare games in a bunch. So that only leaves a few options, especially when you discount the original IPs that rare made but doen't own and went to companies like Mattell and Acclaim.
There are two I am pretty confident with, and are my most solid predictions. NES Battletoads and Killer Instinct Gold. For one, it would feel weird to have the sequel to Battletoads on the service without also having the original (looks at Mario Land), and for the other, if they reveal the SNES port of KI1 in this first batch, why not reveal the N64 port of KI2 in the second batch. It just makes sense.
Now comes the tricky part. The second NES game and the second N64 game. Between the three N64 games that are left I'd have to go with Conker's Bad Fur Day. The original never released in Japan, so I don't think they'd have a problem lumping it in with a group like this and what with Perfect Dark having a new game in development and Banjo being Banjo, I think Perfect Dark and Banjo-Tooie could both be standalone drops at later dates, like they
love doing. I actually was gonna predict Perfect Dark, but then I remembered Conker never released in Japan (so they might not even put it on Japanese NSO, or if they do they'ed have to put a warning that it's only in English like the Japanese only games we have on the service) and that Perfect Dark is getting rebooted.
As for the second NES game, it kind of has the opposit problem. Where the remaining N64 games are all so treasured it feels hard to choose which ones to just lump together in a 4 pack instead of their traditional single game drops, their remaining NES games (aside from Battletoads) are kind of... small potatoes.... I don't think it will be R.C. Pro-Am II or Digger T. Rock. Maybe later (I actually hope they
do come later) but right now they're just kind of throwaway. They don't feel like they should be prioritized. Slalom was the first game they made as Rare... but they have a history as Ultimate Play the Game before that so that doesn't mean much (Rare ZX Spectrum collection on Switch please). Cobra Triangle is fun, so it could be that, but I think I'll put my money on Solar Jetman. It's the only entry in the Jetpac franchise they made after the ZX Spectrum until the reboot on Xbox Live, and it really was their first franchise. Maybe if a Pendragon game had released on NES (Pendragon collection on Switch eshop please) but it's not to be.
TLDR
I think the 4 Rare games coming next to NSO, as indicated by the constelations that may or may not be present at the end of the reveal trailer are
- Solar Jetman: Hunt for the Golden Warpship (NES)
- Battletoads (NES)
- Killer Instinct Gold (N64)
- Conker's Bad Fur Day (N64)
And I'm confident that Diddy Kong Racing, Donkey Kong 64, Perfect Dark, and Banjo-Tooie will come to the service at later dates, possibly on the Switch 2 (assuming it retains the current NSO library). Rare's other miscelaneous titles for other systems... who knows.