Given the unfathomable brand power behind a name like Tim Hortons, though, I think it'd be foolish (that's a lower-case f, folks!) to discount the Canadian icon's turnaround potential. While a supposed "turnaround" has been brewing at Tim's for well over a year now, I think that serious change is coming, with billionaire activist investor Bill Ackman, who remains as bullish as ever on his big stake in Restaurant Brands.