3 years sounds too aggressive of an estimate. I would experientially expect a Macbook Pro to last 5 years. Prior to SSD's, the HDD was the most common reason for laptop failure, but nowadays Macbook Pros come with SSD options, so now I would expect a substantial portion of the most recent Macbook Pro populations to hit the 5 year mark.

In terms of software requirements, I think most people don't play heavy requirement games, and for basic personal and office tasks, the 2/4 threaded CPU's of the past few years have been up to the task of browsing, office suites (with responsive spreadsheets), and media.