It would be a start, though, if we reintroduced keystone species, allowed less problematic predators free reign, and adopted a policy of generally consigning river floodplains to nature as much as possible rather than making rivers into sewers or canals. Trying to live inches from a flowing river is an anachronism from an earlier era when we cared about very different things.
That solution seems to work best through a colonial, capitalist lens. Rather than TINA (Thatcher's "there is no alternative"), consider TIA (Yoda's "there is... another")?
The only long term fix is to move all humans off earth to space/mars/moon/elsewhere, and keep the whole of earth for nature and observation only.
Everything else won't work.
The question is do we all collectively care about the environment enough to all lose our home planet? I suspect no.