I agree with you, and Goiânia is indeed probably phasing out the species when this individual dies. Maybe, even if they don't want to do so, I see a big lack of opportunities for the institution to obtain more specimens; for various motives, such as the lack of available individuals for possible transference, the activists movements involving the place, etc...There was a time in wich the zoo bred the species (yeah, in the old bad exhibit), and I'm happy they no longer find themselves in a situation to continue doing so.
The new bear space is indeed no big deal, definitely. It's just an aceptable exhibit... And you're right, it would be of much better use for other native species the zoo keeps. I would say my preference would be for the jaguars to occupie the place. Big cats in general have some of the most innapropriate exhibits in there, and it would be nice to hold them in a little better space.
For now, I just hope this single bear, who was born there, has a nice life quality while he shares this planet with us, and I also think the sanctuary has nothing more to offer to this individual than what the own Goiânia zoo is already providing.