I suspect the younglings are more activated than ever, what with the barrage of political news they've endured over the last couple of years.
There will have been four years of younguns turning 18 since the Trump disaster, and as younger voters generally trend away from the GOP core tenets of homophobia, racism against non-whites, transphobia and hating women, that's a good thing. Plus the demographics of the US are increasingly trending non-white, which theoretically puts a bit more weight behind the Democrats. That plus disenchanted federal workers pissed off by the shutdown (he'll have lost a good chunk of the TSA's ranks), people who voted for him because they didn't like Clinton but who weren't die-hard MAGA types, any fallout from the Mueller probe... a lot can happen between now and then, of course.
I wonder if there'll be a challenger from with the Republican ranks? That could really fuck up any predictions. Prior to the shutdown, I don't think it would even have crossed their mind. But polls suggest Pelosi's standing has gone up while Trump's has falled further, and the Dems in some polls are now seen as being better on immigration than Republicans, which is VERY rare. And of course support for Trump's beloved wall remains low across the country.
Now he's looking weak, the fear of him campaigning against the losers during their next round of primaries must be diminished. It must look more plausible that he could be taken down - and even if he keeps the job, how much heft does he still have with the average American voter?
And that assuming that the Mueller probe doesn't compromise him to the point that he has to be taken down for the good of the party. From the sounds of it, there's probably going to be a decent case for obstruction of justice with the Donald Jnr/Russians memo he's supposed to have dictated on Air Force One, and campaign finance violations when paying off Stormy Daniels for the affair that came shortly after Melania gave birth to Barron. Could he become too toxic even for the GOP? But this presumes they have a functioning sense of shame, which seems to be in short supply at the moment.