I don't think they could have new uniforms, because a team must wait five years to make a change to its uniform after altering it in any way.
But a team could have a third, alternate uniform as their primary without a waiting period. The Falcons designated their red (third, alternate jersey) as their official home uniform. But that ATL jersey already existed from the previous year, so I don't know if you can introduce a new one like that.
I only type what Buddy tells me he hears.