Some systems already have that. Replaced a switch yesterday and re-arranged some things on my network board and got a HomeKit notification that some things were offline and when it came back. Knowing when something goes offline isn’t as useful as keeping things up though. With something like a hardwired camera/NVR, even if your ISP service is interrupted the cameras can still record, and you can put a UPS there to keep things going, even if the rest of the network is down.
Maybe, though it’s shitty that we got two years, then four more. I held out since the iPhone 7 for the 12 mini, but I feel like 4 years is a good run and I’d like to upgrade this year. I also feel like if they keep the S.E. line going then every other year is better. 4 years feels rough for people looking to purchase in the second half of that cycle.