This battery voltage chart shows a Canique outdoor sensor sending every 30 seconds - from March 2021 until February 2024.

From looking at the chart you can conclude, that 10+ years battery lifetime should be easily achievable.
In 3 years we had a total battery voltage decrease of about 0.1V. Note that the battery cutoff voltage is somewhere < 0.9V. So we can drop another 0.1V at least 4 times before the battery is depleted. That's 4 times another 3 years, or: 12 years to go.