My father had been using a laptop he got in 2011 (I5-2410m) until a few months ago when I bought him a mini PC with an Intel N95, he didn't even want to switch because for the most part everything worked pretty well and why wouldn't it? The i5-2410m is faster than the Celeron N4020, which is commonly found in many ChromeBooks and budget laptops today, and the i5-2410m wasn't even the best mobile processor back then. Many cheap laptops today are also limited to a soldered-on 4GB of RAM, but most older laptops can be upgraded to 8GB.
I have several other laptops from 2011 which are even weaker (One with I5-560M (upgraded from 380M for 6$) and other with I3-2310M) and they are also mostly fine for web browsing and office, and capable of playing 1080p YouTube video even without hardware acceleration (they don't have VP9 decoding),with H264ify CPU usage drops to 30-40 percents.
With progress in semiconductors slowing down i would expect laptops to last even longer, but with manufactures soldering down RAM and sometimes even SSD maybe that won't be the case. Cause if i wouldn't be able to replaces HHD with SSD and upgrade RAM on these old laptops they would be garbage long time ago.
I have several other laptops from 2011 which are even weaker (One with I5-560M (upgraded from 380M for 6$) and other with I3-2310M) and they are also mostly fine for web browsing and office, and capable of playing 1080p YouTube video even without hardware acceleration (they don't have VP9 decoding),with H264ify CPU usage drops to 30-40 percents.
With progress in semiconductors slowing down i would expect laptops to last even longer, but with manufactures soldering down RAM and sometimes even SSD maybe that won't be the case. Cause if i wouldn't be able to replaces HHD with SSD and upgrade RAM on these old laptops they would be garbage long time ago.