Does it make any sense to buy a higher performance machine for longevity?

From my research, it seems like a MacBook Air suits my needs just fine. However, one of the appeals of the Pro that I had was it lasted YEARS before I needed a new computer. So I'm wondering if it makes any kind of sense to get the Pro with higher specs, and it can be a computer to "grow" into. Meaning if it has really good specs now, in 8 years they'll be considered pretty good but not as great as today. Really just looking to stretch my money as far as possible.