The new Hintonburg is... Bells Corners
It depends on what you mean; the traditional mainstreet vibe or the cheap rent/funky business incubator atmosphere.
We're running out of ungentrified main streets, so I suspect the new generators of cool commercial areas will be run down industrial areas, like what happened to City Centre. Call me weird but I think the area west of the old Canadian Tire on Clyde Ave N (Campbell/Boyd Ave.) has great potential especially if the trend towards electric cars spells the demise of the traditional car repair mechanics there. There's enough room for patios and rough infill to create a pretty organic market-like ambience.