More suburban females and blacks will turnout to vote for Biden vs those who turned out and voted for Hilary.
I do agree that the < 30 year old voter turnout is critical as they are the biggest growing demographic in the 2020 electorate vs 2016. Have read that Bernie has not drawn the youth to the primary polls to the degree he claims.
But, if they stay home in November, Biden will have a tougher time beating Trump. If they show up, Biden could win 40 states, as Trump’s base is finite and arguably shrinking.
Link: https://www.pewresearch.org/fact-tank/2017/05/12/black-voter-turnout-fell-in-2016-even-as-a-record-number-of-americans-cast-ballots/