USB Type-c will eventually become the new standard. But they didn't change the current 13".
Crystalwell (edram) will be a first for skylake 28W so the 13" should get a significant graphics boost. Could be they only make it an option so you have to get the i7 upgrade to get the candy.
Other than ports I wouldn't expect too much. They won't slim it too much more given that it will still require some cooling and people still want multiple ports if there is the space for it. It is still possible to shave something of the rounded bottom part but I am guessing they will leave it as is and maybe add some Type-c + new internals.