[Keith]

This Tweet gives a helpful bit of insight about the new studio…

twitter.com 

Interesting that the reply to that tweet says the set may be for NWT too. 

I can’t see how that can be possible if it is also used for Sport.

I think it's important to note the reply was "and maybe also North West Tonight", meaning it's not a definite yet. With the News Channel & World News merging it gives the opportunity to shake up the schedules and move Sportsday (or the equivalent) away from the 6.30pm timeslot. I'd imagine the late NWT bulletins and Breakfast updates would likely use the same alternative/smaller studio.