There are examples of dams being removed where modern fish bypass systems weren’t in place and where it was easier to remove the dams than to modernize them, such as the Elwha River in Washington. That said, according to the Washington Policy Center, the Elwha River hasn’t shown improvement in overall salmon returns or in wild adult salmon returns, post-dam breaching. The communities along the Elwha also haven’t seen an increase in tourism or fishing.
NOAA Northwest Fisheries Science Center: Elwha River
The myth of Elwha Dam removal’s success