Is the machine completely sealed, or where air gets out of the chassis? If it has some cavities where air gets out of the chassis, can air (and dust) also get in? How the chassis is similar to, or different from the previous design in this regard?

https://d3nevzfk7ii3be.cloudfront.net/ig... - Is the black thing on the left side of the screen just an empty place holder? Thinking of the "Pro" Pro (not this "Air" Pro) models with a dedicated graphic card have two fans, this model should have more space inside.