The basic problem is I doubt anyone is going to pay for a brand new stadium. I like the idea that has been suggested here (think it was by madmug but might have been someone else) of upgrading KGV Oval instead, it's near that light rail line they want to put in.I'm not sure they can do much more to upgrade Bellerive. It's in a nice spot right on a beach, but it's also situated right in the middle of a suburban area surrounded by people's houses. Things like parking are a big issue.
The goal with a Tassie team was to upgrade UTAS Stadium's capacity initially (which wouldn't cost much). They'd used Launceston for the big drawing games in the first few seasons while building a brand new stadium in Hobart.