It's an unpopular opinion, but I really don't see how an arena near Temple Meads would be feasible. The traffic there is abysmal, Temple Meads can barely handle the traffic it gets now, and both Brislington and Totterdown rejected any plans for RPZ.
I'd love a central arena, but without significant investment in the train station AND a dedicated car park that can get people to Temple Meads (i.e. a new local station) I don't see how it was feasible.
With that said, the entire point of moving was to start right away. With the mayor now gone there's no incentive to complete, so I would put money on it never happening now...