Howe long until apps will stop being supported for iOS 7?

I'm buying myself an iPhone 4S 16GB For my birthday from a 2nd hand store.
I'm not planning on upgrading to iOS 8, Mainly because I have heard that it does not work very well on iPhone 4S.

If I want to stay with iOS 7, How long will it be until everything needs iOS 8.0 or higher to be able to work?

My main apps are facebook, tumblr, snapchat, kik, instagram, etc.
I don't really use my phones for games, mainly social networking and music for when I'm out.

Within a year or so. IOS 9 is being announced later this year mean IOS 7 will be 2 full updates being. Support for IOS 6 has already stopped, so given that it is 2 full updates behind, i'm assuming IOS 7 will follow a year from now.

However, if you already have them installed then you can continue to use them, you just won't receive the updates.

Most will probably still create apps for iOS 7 because there isn't really no extra effort. When it went from 6 to 7 it was a major overhaul so no one supported 6 anymore because it was to much work. Thats not the case right now.

Then again if stats start showing that only 2% use iOS 7, I see no reason why developers would keep supporting it.

I get that you don't want IOS 8 but if you don't upgrade to it and something happens to your phone and apple needs to fix it they will not fix it if you do not have the latest software on it. It is one thing if you device doesn't support the latest software but if it does then you have to update to it or else apple isn't really supposed to fix it.

Apps compatible with iOS 7 will stay available in Apple's App store for many years, my take is maybe as long as 5 years. To give you an example, there are still apps that support the 3GS and 4 models (3GS came out in 2009, 6 years ago and used iOS 3!). Of all apps in the app store, more than 50% (half!) still support iOS 5. And we're at iOS 8 today (3 generations later).

So iOS 7 apps will be there and available for many years -- from past data it should be around for 5 more years.

You can keep using an earlier version of an app as long as you want (and as long as the developer/author supports it). Facebook, tumblr, and other major companies keep their older apps for compatibility (for users like you). And they upgrade them every once in a while to keep users happy (and to fix their bugs).

Though be careful upgrading your apps if they're older. Sometimes developers don't do a good job testing their older apps -- they spend more time testing their latest version. So the older app can have more bugs and fail for you. Don't upgrade an older app if it's working fine for you. If it ain't broke, don't try to fix it (don't upgrade).

PS: The earlier "anonymous" answer here is wrong - they're saying "support for iOS 6 has already stopped". This is not true. What they misunderstood is that some developers/authors are stopping supporting THEIR apps -- this doesn't affect all apps. Major companies don't remove/stop support for their older apps You'll see many iOS 6 & 7 apps still in the app store -- you can download them now & for a few more years.

Apple has a policy to keep (leave alone) older apps -- they let the developer (author) control how long they want to let their app stay. This is why most major developers/companies have and support more than one version of their app, for different iOS versions (and it lets them keep their older AND newer users).

Have a friend that has a 4s on iOS 8, no complaints. I've used it as well & it runs fine. Although it may not matter since it may already be on iOS 8 for all you know.

As far as the iOS requirement its up to the developers of the apps. Some may never require iOS 8 specifically, others already do. You'd have to check to see which of those apps already do require it or not.