We will eventually have a Democratic president who oversees disastrous economic times and/or an unpopular war, and there will be a realignment due to the self-correcting nature of our politics.
There wasn't a realignment in 2008 when Bush presided over both.
The national popular vote swung Democratic by 9.6 points, and Democrats picked up 113 electoral votes by flipping nine states plus NE-02. That's pretty significant.
That swing largely came from the financial crisis hitting at the right time. McCain and Obama were neck and neck in the polls even with Bush's unpopularity before the crisis hit.
A realignment has lasting effects on both Parties. The new realigning majority coalition usually wins at least 3 consecutive presidential elections, the realigning President performs far better in their reelection bid, and the new majority coalition forces the opposition Party to moderate. The Democrats didn't win a third consecutive term in the WH and Obama performed worse in 2012 than 2008. The Democrats got swept from their own trifecta into a GOP trifecta 8 years later. Plus the Republicans did this by not moderating at all in 2010, 2014, and 2016.
I'd argue that we're still in the Republican alignment era that started in 1980.
My point is that a wave election will encompass all voters involved. Non-white population can keep growing, but margins will self-stabilize in the event of a disastrous Democratic presidency. Black, white or purple, the American public will want change. That will eventualize into minority voters swinging to the right.
