The average console life span used to be 5 years. Now, that has slightly increased in the last 15-ish years (Wii and 3DS lasted 6 years, Xbox 360 lasted 8 years, PS3/PS4/Xbox One lasted 7 years), but it's worth noting that the average console lifespan used to be 5 years. NES came out in 1986, SNES in 1991, N64 in 1996, GameCube in 2001, and Wii in 2006. The Switch came out in early 2017, and it was running on tech from like 2015. If you're right that the Switch lasts 3 more years, that means it's gonna be a console that sold for 9 years before getting a replacement. I think the original Gameboy might be the only longer lived console

Tl;Dr: the Switch was outdated when it came out, 5 years and 9 months ago. The average console usually only lasts about 5 years. I guess the pandemic and the chip shortage are causing delays to the next Nintendo console but the Switch has already lasted longer than anyone would expect.