I had a single speed Jacuzzi that lasted for 20 years. It started getting noisy which I took as getting near the end. I upgraded to a 2 speed pump for savings on the electric bill. I run it on low 95% of the time. High speed only for chemical dispersion. Like you I did a rehab going to salt, new filter, new liner and cover. 15 years is pretty good but the noise could be a bearing starting to wear.
I am very pleased with the 2 speed option.

In NJ, I usually see about a 7 year life from an induction pump motor, single or dual speed. Most pools are off from Nov through April. Sealed permanent magnet motors on pools have not had any wear issues that I have seen and expect a very long life.

Down South, its more like 2-5 years for induction motors, depending on usage.

Please don't confuse pump life with motor life.

Scott