There's a reason why Tesla picks 10 years (8 years for car batteries) as a warranty period. Ask yourself: why 8 years and not 10 for cars? Why 10 years and not 15 or 20 years for home batteries? It's not arbitrary.
Battery degradation is not linear. It's not like: 10 years = 70%, 20 years = 40%. It's probably closer to 20 years = 20 % capacity left. The decay becomes exponential-like after a relatively linear period of roughly 10 years.
The Tesla warranty will fall under "first life" in the image in the link above.
So batteries (even Tesla Powerwalls) do degrade and do degrade to the point where you need to replace them a bunch of times during lifetime of a house.
Tesla and other car makers set their warranties at the mandatory minimums. Why would they offer more when they don't have to and consumers find them long enough and/or other car makers aren't competing on warranty length? That doesn't tell you anything about battery longevity.
Edit: Does my MacBook Pro die after 1 year when it's applecare warranty is over?
The mandatory minimums? Got a source of the mandatory minimum for cars (US and/or EU) as well as power walls?
The fact that other car makers aren't competing on warranty length seems to me to prove my point, but you seem to think it doesn't? What I mean is: if battery degradation for cars isn't that bad after 8 years, then why are other brands not offering significantly longer warranties to compete with the Tesla one?
Not sure about the competition argument anyway, since Tesla didn't have any competition initially and arguably still doesn't have real competition (depending on what features of the car you value most).
Edit: Does my MacBook Pro die after 1 year when it's applecare warranty is over? --> Pretty close yes IMO. My personal experience is that my laptop and phone battery capacities degrade very fast after 1 year and need to be replace after about 2 years, 3 years if you really really push it and are OK with constantly charging.
RE: MacBook Pro dying close to a year right after it's warranty it over --> well now you're just trolling. My iPhone 15 pro battery still maintains 100% battery health a year after its manufacturing date. It obviously won't need replacing in 1-2 more years even if I "really really push it and are OK with constantly charging". I used an iPhone XS until last year after it was about 5 years old, 5x longer than your supposed device-dead date. I don't think this is unusual.
Battery degradation is not linear. It's not like: 10 years = 70%, 20 years = 40%. It's probably closer to 20 years = 20 % capacity left. The decay becomes exponential-like after a relatively linear period of roughly 10 years.
If you want to get an idea, this is what the decay of battery capacity roughly looks like: https://www.researchgate.net/profile/Simon-Montoya-Bedoya-2/...
The Tesla warranty will fall under "first life" in the image in the link above.
So batteries (even Tesla Powerwalls) do degrade and do degrade to the point where you need to replace them a bunch of times during lifetime of a house.