It doesn't sound like much in the way of news, as it sounds more like someone important on TF4 thinking out aloud while looking over the props from earlier TFs movies.
As such, the comments make it sound like the Cube is not in the script, but is likely to be in the background somewhere like Frenzy's head in TF2.... although, I'm not sure how it would be explained without something scripted, as we all know that the Cube was destroyed.

It makes for an interesting article though, with a few insights into how Movie Props are used and abused.