A change? Apple using a non-standard connector is very rare. Standard connectors are Apple’s norm. The iPod dock connector is unique, but it had to serve widely-varied functions in a thin format; and what other devices would you want to plug into that cable anyway?
As for USB, Firewire, and Thunderbolt, they’re standards and I’m glad Apple adopted them early and dragged the rest of the world along. (And none of them prevented the use of older gear. Even USB would work with ADB devices using an iMate adapter.)
And then there’s the micro-DVI port on my Air... but a full-size DVI (or VGA) port simply wouldn’t fit. So adapters were necessary to connect those giant plugs to the thin machine. Mini-DVI wasn’t a rejection of devices people already owned; its entire purpose was to connect those existing devices.
Lastly, look at the iPhone: it’s commonplace among cell makers to use non-standard headphone jacks. But Apple never did. So there’s no surprise that Apple’s plans continue to involve standard headphone jacks.