Valve did allow RetroArch on their store, it's just Dolphin which got shot down. IIRC the distinction was that Dolphin flew close to the sun by bundling decryption keys, which gave room for Nintendo's lawyers to argue that it violated the DMCA, and Valve didn't want to die on that hill for the sake of putting a free emulator on their store.
The courts are still determining this, and it's an evolving topic, as evidenced by Nintendo's recent actions against a Switch emulator [1].
In particular, DRM circumvention technology is explicitly illegal to distribute in at least the US and EU, in a way that goes beyond regular copyright law. (The DMCA in the US has some exceptions specifically for video game archival purposes, though.)
Older games usually didn't have DRM in that sense; the concern back then was bootleg game copies, or unauthorized games [2], which the original consoles tried to detect and reject using "inverse DRM" techniques (i.e. the console authenticating the game, not the other way around). But newer games and consoles do explicitly feature DRM that might well be considered covered under the DMCA.
I don't think anyone can make qualified predictions on whether courts will find them legal at this point.
If you really believe that, I suggest running a 30 second search for "<retro console> emulator" in the Google Play store. Some of them are even paid, with Google earning their 30%.
No they won’t. Emulators are legal. If you’re thinking of Yuzu, they crossed many lines into illegality, specifically offering support for currently sold games/systems, as well as breaking encryption.
It’s not even just current games tbh, one of the things that cooked their goose was trafficking in pre-release games, which is legally relevant because it demolishes the “we’re just innocently emulating hardware/supporting homebrew” argument. Demonstrating intent is absolutely legally relevant.
1. https://www.theverge.com/24100979/altstore-europe-app-market...