I'm not sure whethere all of the current Arena's status information is needed to be placed there, but I think that Expansion information is proper for this page. Maybe at the "Economy" box.
I think it is sufficient to summaraize it with the "Time until completion", and the number of total seats that are being built.
This is a low priority feature, that will just make it a little more user-friendly, as this page is all about summarizing the important status of the team.