How long could this version of MacBook Pro be in use

It will currently run the latest operating system Big Sur

We do not know when Apple will want some minimum hardware that excludes your Mac. A Mac tends to still install the latest macOS release for anywhere between 7 to 10 years. There are exceptions, especially for less expensive lower capacity models.

Once the Mac can no longer run the latest macOS release, Apple will support the prior 2 releases with security updates, so you are still supported for an additional 2 years on the last version you could install.

After that, you just have to be careful about what you install, and maybe find a web browser that still runs on your macOS release, but the browser still releases new secure versions.

I have a 2007 Mac mini that still runs an old Snow Leopard 10.6 release doing backup services for me within my home network (that is to say, it is not surf'in the web, and making connections outside my home).

I have another 2011 Macbook pro also doing backup services running El Capitan 10.11 (also not going out on the internet).

My current personal Mac is a 2016, which is still going strong, but when I decide to replace it, one of those older boxes mentioned above may be retired and this Mac put in their place.

Ask a question related to an Apple product or service and perhaps someone here will help you answer it. That's how.

For as long as it continues to work. I'm not sure what other answer you're expecting.