Looks like they'll be sticking with the simplistic design we all like about it. Interior seems to be painted all black by default as well, alongwith the back panel. Power/Rest buttons and other LEDs might be located at the top near the USB ports and headphone jack. Water cooling holes are now located at the top. Side panel fan placement is in line as well.
Doesn't seem like a worthy 'upgrade' for current CM690 owners like myself. Wouldn't expect a whole lot difference in interior design too. Looks more polished and refined basically. Point out any other little details for us if you can please.
360-degree view:
http://www.coolermaster.com/upload/360/RC-690K_360.swf