Depends on what the left/centre left parties manages to propose. WIll they provide new corporatist alternatives such as Hillary and Macron? And thus leave most to either stay home or vote against a far-right populist alternative? Or will there be a more progressive alternative that younger liberals actually feel represent their views?

In terms of topics I would say the biggest one will be between those who believe free speech must be preserved at any cost, versus those who will eagerly sacrifice it at the altar of social justice and identify politics (i.e the far "regressive" left), or give it up under the delusion that giving up some of our privacy on the internet will somehow radically boost our security against terrorism (i.e Republican right).