Iphone 6s Obsolete

Apple never disconnects any one’s device. People may continue to use a device after it’s hardware is no longer supported (see -> Obtaining service for your Apple product after an expired warranty - Apple Support) for as long as the device suits their needs or wants.

As for how long Apple provides iOS updates for an iPhone model, there is no published support document stating a policy for that. Again however, just because a device is not compatible with the latest iOS version does nit mean it ceases to function.

Hello,

Each new iOS version comes with a list of eligible devices. Below I copied the list for iOS 15. That being said, each feature included in iOS has different eligibility. The older your device's hardware the more new features will be unavailable.

Apple would likely make an announcement about eligibility but its possible you would miss it of you are not watching their Newsroom

iOS 15 - Apple

"iOS 15 is compatible with these devices.

Learn more about iPhone

Learn more about iPod touch

• iPhone 13
• iPhone 13 mini
• iPhone 13 Pro
• iPhone 13 Pro Max
• iPhone 12
• iPhone 12 mini
• iPhone 12 Pro
• iPhone 12 Pro Max
• iPhone 11
• iPhone 11 Pro
• iPhone 11 Pro Max
• iPhone Xs
• iPhone Xs Max
• iPhone Xr
• iPhone X
• iPhone 8
• iPhone 8 Plus
• iPhone 7
• iPhone 7 Plus
• iPhone 6s
• iPhone 6s Plus
• iPhone SE (1st generation)
• iPhone SE (2nd generation)
• iPod touch (7th generation)"

I hope this helps.

We don't really know.

But there are Beta versions that are publicly tested. If you join the program you might be able to find out whether the 6s will be supported in future versions of iOS. However, at this point the 6s is clearly supported for any version of iOS 15. If it's not supported for iOS 16, it will then be supported for future incremental versions of iOS 15.