Yep.
I have a handful of Vintage Macs and while there are no updates and haven't been for eons, they can still connect to Apple's update servers. My first generation iPad and my old iPhones running OS's as old as iOS 4 can still open up the app store. It's not a great experience because the App Store doesn't filter out only apps compatible with your device. But if you happen to find an app that still has an old version uploaded that's compatible with iOS 4, it'll still download and install. It still checks for updates. In fact most online services still work; except those that have been totally deprecated by Apple.
And in fact if I, today, wanted to do a fresh clean install of Mac OS X Tiger on a G4 iMac sitting next to me, from the original retail DVD, it would then connect to and download the latest updates (from many years ago; but still newer than what's on the DVD) and install them from Apple's servers. We're talking about an OS from 2005.
I understand that bandwidth and server resources aren't free but; Apple for all of their warts have always done an exceptional job of keeping things online. At the end of the day these are still devices that have limited ability to have software installed any other way than official channels, and Apple COULD decide to stop supporting them and turn them into bricks. But the fact of the matter is this hasn't, historically, been the case at all. If you buy a AAA game on your device it will likely be able to be downloaded for many many years.
The one caveat to that is that the Apple update cycle is much, much faster than consoles. And Apple doesn't tend to prioritize legacy support when they update iOS (or even macOS for that matter). So if the developer doesn't keep up with updates, there IS a real risk that whatever device you have in your pocket won't be able to play your $40 game. You'll have to dust off an old device to play it.