I'm going to make the case that your obsolence argument is invalid.
iOS 8.3 still supports the iPhone 4s, which was released in 2011, 4 years ago. (I know there are locked-in android models where manufacturers have denied devices updates, though.) A two year old phone isn't even obsolete by capability anymore either. Nearly any app will work on a model made in 2013.
Ditching your phone just because the battery doesn't hold a charge is a bit shortsighted... the batteries are cheap, and service can be had every hundred feet in a lot of malls. If my iPhone 5 battery needs replacement it'll cost me all of $20, installed. The most expensive service you can buy in a local repair shop for my phone is $89, parts and labour included. That's a full screen replacement without having to send the thing away.
So I question the idea that a phone has a 2 year lifespan.