That is it, and the connector beneath the HDMI port is the same (but mounted) JTAG connector as the RPi2.

I don't know what is the chip, though.

Also noticed a 2-pin header between the 40-pin one and the upper USB ones: it looks like the "RUN" from the Rpi Zero.

EDIT: The 2-pin "RUN" header already existed on the RPi2, where the ceramic antenna is now located on the RPi3.