New dock connector is physically stronger than the old one with contacts sheltered inside a solid metal body. No need for headphone jack for structural reasons.
It appears the new connector could be MagSafe as the bulk of the ferrous body is near the plastic shell with the tip mostly hollow, filled with plastic and the few contacts. The entrance hole on new iPhone seems to have an unusual shape, possibly wrapping magnet around it, sucking the ferrous part of the connector in.
We've seen 8 contact each side plus metal body which may or may not serve as ground - likely not. As there does not appear to be any keying feature that would prevent users from inserting in either orientation, it may be that both sides carry the same 8 signals, but perhaps there is a way for the iDevice to tell which way it's plugged in to re-map the signals which would allow for 16 signals total.
Analog audio and video is gone from the dock. So is UART serial interface. If necessary, the relocated headphone jack offers stereo output, mono input and serial communication to build a simple accessories.
New dock connector must support USB 2.0 and Thunderbolt / DisplayPort. This covers audio/video I/O with as few pins as possible. And I can't see what else would be missing once we have that. Still, 8 might prove to be too few unless Apple plans to reconfigure pins on the fly based on which cable is connected.