Calgary is larger, more walkable city and millennials are nostalgic for things like markets . I don't think it is absolutely necessary to be directly connected to transit for a market to succeed. The important thing is to keep it simple and authentic. Another mall with brand retailers and a market component will just fail again. That's dated.
I think there is some cultural components to this - Calgary's core has been largely bleached of small, independents or non-corporate minded businesses and organization due to the 1980s - 2015 office-focused, O&G boom (apart from Chinatown). Wildly expensive land, speculative development priced for mega-developments all but erased the ability of an independent market type use from competing.
Where downtown markets have happened, there is often government intervention of some sort: Vancouver (Granville Island), Montreal (Atwater and Jean Talon market), Winnipeg (the Forks), Toronto (st Lawrence market) all have publicly-owned lands/buildings as a core component at least for some or all of the market's history.
Calgary has few champions for such a project - stampede would be a natural fit but they, ironically, don't seem interesting in agriculture as a practicing business and would rather have their taxpayer-funded parking lots sit empty 340 days a year. Also, unlike almost every other major Canadian city, we have no pro-urban MLAs or MPs that have championed similar projects throughout history, a crucial support level that has always been missing in downtown Calgary.
Calgary did have a public market until 1954 when it burned down.
Now would it be crazy to have a public market run by a non-profit in the core in an age of privately run supermarkets, uberEats and Costco mega-centres? Not really, we seem perfectly fine to have publicly funding recreation centres and arenas competing against private recreation facilities for decades. What it would take is vision and leadership.