If she's was much younger Waters would be the perfect candidate to go against Trump. Waters is a fierce leader who would hopefully overcome the barrier of being a WOC against a media that is eager to take down any powerful women willing to challenge the patriarchy. I couldn't think many congressional people who could help unite the Democratic base, as just about all self-identified Democrats I know absolutely worship her. The main thing challenging her statue beyond her age and just being a congressional representative is the racism and misogyny that pollute the country, though Trump unpopularity could help secure a victory for Waters.
