I think Anton has generally been very thankful to his partners, and always seemed more sad for them rather than himself. Because of the partners he tends to get, I think he has a knack of just taking them as they are, knowing their limitations, working with whatever strengths he can fine and just enjoying the ride while it lasts (without showing obvious signs of frustration for their benefit). He tends to see the friendship as a win as well as just the dancing in the show. Whether he looked sad I'm not overly sure, he seemed more or less the same to me, as complimentary as ever and with the usual 'joy to work with' line as normal, so I don't really see him being anymore sad or different on this occasion, but I confess i don't take the time to dissect him in this sense.
Anton has been rumoured to be going plenty of previous series (and become the host post Brucie). Brendan also constantly thought by some to be just going through the motions and on his way out, but both are still here (even when other as efficient Pros have been replaced (i.e. Ian Waite, Matthew Cutler, Brian Fortuna etc).