No, the park haven't confirmed anything yet but honestly I don't think they will until it is actually done/has happened, simply because they announced Submarine Splash only a few days before the ride opened to the public. Once we start seeing things move or appear in Thomas Land I think it's pretty safe to say yes but for now it's just a rumour. I do think it will happen though - since the exhibition is moving back into the area there is really no point in going down to that back end of the park as from what I've seen Terrance is not a very popular attraction in the first place.Do we even know if he is 100%moving?
Plus, in the 5 year plan it mentions zoo redevelopments which could possibly be done in this area and if they were I think it would be pretty weird to see Terrance in a random bit of the zoo.