The amount of engineering that goes into making devices work over the huge installed base of cat5/cat5e/cat6 twisted pair is pretty amazing; I was amazed Gig-E worked, let alone 10GE.
If there weren't the huge installed base of wires in the walls of buildings, we probably would have different standards for patch cables instead of fairly obscenely complex network interfaces.
all use Ethernet and standards are set for them, all peripherals need to talk to it in same protocol and newer devices should be back compatible .
But with lightning you can design cables which need not use device computing power for all transformations, it is pretty smart, they built this cable for the next decade we will see interesting applications from apple and its partners in coming years
The protocol certainly is not same and not exactly backward compatible. 1000-Base-T is fairly complex interface that is more similar to S(H)DSL than to traditional ethernet over TP or even anything that would any sane person call "baseband interface". By the way this is the reason that SFP/GBIC to 1000-Base-T transceivers are not supported by all devices with relevant slot, are not exactly compatible between manufacturers and sometimes are not compatible with non-gigabit devices on other end of the link (ie. not backward-compatible on the RJ45 side of things).
And before than in the days of first fast ethernet implementations there also were incompatibilities of similar type, which is mostly the reason that every managed or even "smart" switch allows you to disable auto negotiation quite prominently in it's configuration interface. Although that was more about software issues than about interoperable implementation being non-practical as is to some extent the case with copper SFP modules.
Bottom line: "I don't know what the next network interface will look like, but it will be called Ethernet and use RJ45 connectors on CatN (for some value of N) twisted pair ..."
If there weren't the huge installed base of wires in the walls of buildings, we probably would have different standards for patch cables instead of fairly obscenely complex network interfaces.