It’s not certain if this applies to Model 3 owners, or if all of the road-model Y examples will get the update. The Y has only been on the road for several months, so there’s a chance that will cover all current models.
Tesla previously improved the range through the program, adding 15 miles to some versions of the Model 3. In 2019. However, this can easily be welcome – and important when the range is crucial to fend off competitors like Volkswagen ID.4.