Edit. the fire emblem game that got a limited time release is NES not gameboy, mb
So let me state a few things about the current situation as I’ve understood it.
The limited time sale for some reason started far before the year they are celebrating and even ends to celebrate it.
the 3d collection had more game files referencing other titles that were tested on the software used to run the old games
[https://www.nintendolife.com/news/2020/09/super_mario_64_emulator_in_3d_all-stars_includes_references_to_other_n64_titles](https://www.nintendolife.com/news/2020/09/super_mario_64_emulator_in_3d_all-stars_includes_references_to_other_n64_titles)
Additionally, Pokémon is celebrating its 25th anniversary THIS YEAR.
[https://25.pokemon.com/en-us/](https://25.pokemon.com/en-us/)
And something id like to bring into discussion, NES and SNES games, nes games are kind of running out for the switch and snes games are filling up
But a feature they added was that now you can sort by tabs which game console its based on, this feature was added a while after the 3d collection got released
For some reason Nintendo have not launched a Retro Store on their Eshop, which is strange tactics keeping people from buying old 64 and gamecube games
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Now il bring the theory i think whats happening
The Super mario 3d collection was to test run the emulation for the older consoles.
Also they were testing other games on the software used to run the 3d collection
They might begin releasing more games for more consoles now in 2021 to celebrate the 35th anniversary of Mario, And coincidentaly the 25th anniversary of the pokemon franchise.
So my money is on that n64 games will likely be announced to come to the nitnendo online service this march 10th and gameboy games either then or later this year to celebrate Pokemon.