They'd need to add a second HDMI in port. One for the cable set top box and one for the blu-ray player that you'd have to buy in order to watch your DVD and blu-ray movie/TV show collection.
Greenberg said "No" as the first word to the response. If the discless Xb one is on the cards, but he wanted to keep people guessing he wouldn't have started with "No", he would have just gone straight into you can't believe everything. If the discless Xb one does turn out to be real it pretty much makes this tweet a lie. Greenberg might be a spin doctor but I don't feel like he's a liar. Of course I would have said "It's complete BS, stupidest idea ever." if I wanted to leave no room for ambiguity.
It may be an idea that's floating around MS as a possible response if they really start falling behind PS4. So while it's a no now, it may become a yes later on. I think before they push any panic buttons they are going to see how the USA settles down once PS4 supply can meet demand. If they are going toe to toe with PS4 in the USA after PS4 supply and demand balance out I don;t think there's much need to panic.
Besides, I don't MS can do anything much to reverse what's going on in Europe, I certainly don't think a box without a Blu ray drive at the same price as PS4 is going to do anything for them in the markets where they're struggling. Europe didn;t care about Kinect on 360, and it most probably doesn't care about Kinect on Xb one. In fact the best think MS can do in Europe is release a $379 Xb one without Kinect. Europe would be O_o about discless sku at same price as PS4, and it would be 
about Kinectless sku at a lower price than PS4.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
