Apple standard is 6-7 years for latest OS support. My 2017 Intel MBP still going strong. Had one free battery replacement because this generation of MBPs plagued by quality control issues — butterfly kb, poor hinges, poor heat management, highly sensitive to dust.
Of course, it won’t get Sonoma but still very useful for occasional out of the home/office work (ie, airports, coffee shops, libraries, …). Plus since I mostly VPN into office/home assets, it’s more of a dumb terminal now and offload heavy workloads to beefier machines.
Don’t be too worried. Open Core Legacy patcher will keep your MacBook running on the latest operating system for many years. I put macOS 13 Ventura on my 2011 MacBook Air and it ran very well. 
I made the fatal mistake of buying an Intel 2020 MacBook Air in August 2020. I was 17, saved up all my money and didn’t care about Apple silicon.
How long until they kill my 3 year old computer?
Fall of 2025 if you’re (un)lucky
Apple standard is 6-7 years for latest OS support. My 2017 Intel MBP still going strong. Had one free battery replacement because this generation of MBPs plagued by quality control issues — butterfly kb, poor hinges, poor heat management, highly sensitive to dust.
Of course, it won’t get Sonoma but still very useful for occasional out of the home/office work (ie, airports, coffee shops, libraries, …). Plus since I mostly VPN into office/home assets, it’s more of a dumb terminal now and offload heavy workloads to beefier machines.
Don’t be too worried. Open Core Legacy patcher will keep your MacBook running on the latest operating system for many years. I put macOS 13 Ventura on my 2011 MacBook Air and it ran very well. 
https://dortania.github.io/OpenCore-Legacy-Patcher/