I have an iPhone 5. How long until that phone will be too old? Will it be able to get IOS 9?

I'm gonna upgrade to the LG G4 in the next couple years. I just wanna know how long my iPhone 5 has until its considered an "old" phone.

Yes it will get iOS 9, but will not get iOS 10, though it would still be able to run most apps for years to come.

Currently the original iPhone & the 3G are considered to be obsolete in the sense that neither gets updates, are sold new & can't run the majority of apps.