You're assuming the people who currently do not vote are less liking to follow the herd. I'm skeptical.
That's true, but they aren't following the herd now, so that seems a fair assumption in my mind.
Hard to predict how that plays out.
Presumably most of the effort and money spent to keep people from voting stops. So that effort and money will be redirected to convincing new voters to vote the "right way."
This is mainly a problem for the GOP. It has been an effective strategy for them to discourage certain demographics from voting - to the extent that those demographics tend to vote for Dems. Blacks, Hispanics, the poor, the young, students, those dependent on Social Security and welfare.
But if they are now have to vote, the GOP will have to invest in changing that lean from Dem to GOP. That's a whole new campaign philosophy from rallying the angry white guys and the religious nuts. The strategies that rally that GOP base - anti-immigrant rhetoric, protecting the hard-earned wealth of the billionaire class, the appeal to war, and denying aid to the poor and needy - these pitches won't work nearly so well on the people you used to keep from voting.
I have confidence that the GOP will figure it out. They are much better propagandists than the Dems. But I don't think they can pull it off without sending great ripples of change through warp and weft of America's partisan fabric. It would be interesting to observe. A shame we'll never get a chance to see it.