Apple will be contacting upgrade-elgible iPhone users with older iPhone models via email to come into their local Apple Store to update to a new iPhone 5s or iPhone 5c.
This new upgrade initiative is said to fall in line with Tim Cook's ongoing plans to boost iPhone sales at Apple Retail Stores, something already underway through trade-in programs, App Store app updates, iBeacon integration, and more.
The iPhone 5s and iPhone 5c are both top-notch products. It'll be interesting to see, however, what Apple offers to get people to upgrade now and not wait until the presumed iPhone 6 launch in September. Not everyone cares about the latest and the greatest, as iPhone 4s sales proved last quarter, just getting a soild phone at a great price.
If you receive an upgrade offer letter from Apple, let me know! And let me know if you take them up on it!