Mindboards

Is there any reason to believe the EV3 would not be RCX compatible? (for Legacy Sensors/Motors)

IMO, no.

There is absolutely no reason for the RCX motors, touch sensors, and temp sensors not to work. In order for the light or rotation sensors to work, the HW would have to support it (which it probably does, since the NXT Ultrasonic sensor uses similar functionality), and the FW would also have to support it (I have no idea if it does).

Cool. Thanks for the confirmation. Would have been nice if they posted "RCX" compatible too, but since NXT adapters back convert to RCX maybe it is assumed.