If he wants to stay, offer him a reasonable 12 month deal. If he fancies two years in the sunshine, he can go with our best wishes.
Until Adam tells us where he thinks his future lies, everything else is speculation. Personally I'd like him to stay for another season, then be given a Coaching role within the Academy. He would be great at mentoring the younger players who are just starting out in the game. If he and his missus want a new life in Australia, good luck to them. Whatever happens, we can only wish him all the best as one of those rare players, who seem to have endeared themselves to the grass root support of Barnsley FC.
Maybe the Australian leagues about his standard these days. Maybe worth keeping as a squad player if we go down, no more than that