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With a Switch 2 looming, Nintendo is sending out the original with a bang
(www.theverge.com)
This is a most excellent place for technology news and articles.
For all Nintendo's faults (and boy do they have them in spades), Nintendo are pretty good for this.
Gameboy Colour could play Gameboy games
Gameboy Advance could play GB/CBC
DS/DS Lite could play GBA
3DS could play DS
Wii could play GameCube
Wii U could play Wii
To me it'd be very surprising if the Switch 2 couldn't play Switch games.
Generally unless they want a serious form factor or major architectural change, Nintendo retains backwards compatibility.