Apple has a long history of removing established technology standards that it thinks will be obsolete.
The iMac dumped the floppy disk drive, the MacBook Air dropped the CD/DVD drive, the iPhone 5 killed the 30-pin connector, and the new MacBook eschews every port for a single USB-C port. When Apple removes hardware features, people get pissed.
Rumor has it Apple will ditch the 3.5mm headphone jack on the iPhone 7, and the well-connected @OnLeaks is now corroborating the rumor with what he claims are legitimate iPhone 7 cases.
As you can see in the images above, the purported iPhone 7 case looks pretty similar to an iPhone 6S case. But instead of a hole for the 3.5mm headphone jack on the bottom left, there's another elongated cutout for what is presumably another speaker. If true, the iPhone 7 could be the first iPhone to have stereo speakers.
How will people listen to music with headphones then? It's believed the iPhone 7 could come with new earbuds that connect to the Lightning port. To provide backwards compatibility — and temper fan outrage — Apple could also include a Lightning-to-3.5mm headphone jack dongle with each new iPhone 7. Though, it's just as likely Apple could sell an overpriced dongle separately.
While nothing is official until Apple says it's so on stage, all signs point to the headphone jack going away.
With all rumors, we advise taking the news with a grain of salt. A leaked case is typically a good indicator of what's to come, especially when it's coming from a reliable source, but there's always the possibility the schematics are fake (or they're designed for an iPhone clone, of which there are tons coming out of China).
If the thought of losing the headphone jack upsets you, fret not. Apple's rumored 4-inch iPhone SE, which is expected to be unveiled on March 21, will likely maintain the port.