Please remember to take rumors with a grain of salt.
From what I have heard I wouldn't get too excited about new Battle and Crisis Suits as they aren't getting new models.
They will have recut sprues with more weapon options but the models themselves will remain the same AFAIK.
However there will definitely be some other brand new Tau models.
From what I remember being told the suits themselves remain pretty much the same, I was told the sprues had been recut to allow more options.
I am assuming that means weapon options, with the kits going all plastic.