Some time ago (in 2017) when HW2.5 came out. Elon Musk tweeted it as a modest performance improvement with additional redundancy. Said that if it turned out to be necessary for FSD that owners with 2.0 that purchased FSD would get a hardware upgrade for free. (paraphrasing)
So, while it looks like cars are now starting to get HW 3.0 in production, it wouldn’t shock me if 3.5 or 4.0 came along before true legal & functionsal FSD does. So maybe we shouldn’t be in such a big hurry for a HW upgrade install until the software can do anything with it that provides any additional functionality. On the other hand, It is clear, however, that there are features rolling out to 2.5 cars that are not available to 2.0 cars. TeslaCam...
So, if you have a 2.0 car, getting HW 3 would likely provide additional features immediately.