What Does The Tory Win Mean For The US?

Not much.

There is a tendency to overdetermine comparisons. The Brexit vote of 2015 was largely seen as a precursor to Trump's election in 2016, so there is a natural tendency to see Johnson's win in 2019 as a precursor to Trump's re-election.  While Trump might very well get re-elected, the British general election doesn't tell us much about what might happen here.

There are some parallels though. With most constituencies reporting, Johnson and the Conservatives have won 43.6% of the vote which is significantly below what Trump won in 2016 (46.1%).  If you add the Brexit party vote to Johnson's, you get 45.6%.  So Johnson won a sweeping mandate for Brexit with....a minority of the popular vote.

This is the way British elections always work. A minority of the popular vote can create massive majorities in the Commons, if the other side splinters.  Let's look at the left and left of center vote in Britain.  Labour collapsed to 32.2% of the vote, and Lib Dems won 11.5%. SNP won 3.9% and the Greens won 2.7%. Add those up and you get 50.3%. 

Labour's problem were twofold. First, Jeremy Corbyn was very, very unpopular. So, if Democrats want to take a lesson from Britain...don't nominate someone who is very, very unpopular.  Secondly, the Left splintered into warring factions over the issue of Brexit and how far left to move.  So, don't do that.

If anything, Johnson's victory looks like Trump's in 2016. Johnson and Trump breached the "Wall" of traditional supporters. Trump won PA, MI and WI.  Johnson won the Midlands and Northern England seats of working class Britons.

But Johnson also probably won, because a substantial number of the English want Brexit over and done with. Screw the consequence, let's get out.  You could make an argument that Biden is the best positioned (maybe Buttigieg) running on a "Let's get out of this cycle of craziness." People are exhausted by Trump, the way Britons are exhausted by Brexit.

Certainly, Warren and Sanders will need to explain why moving the Democrats fairly far to the Left is a good idea, but neither Warren nor Sanders are anything like Corbyn, really (except for their fanatical online supporters).

Also, if Johnson pushes through a Hard or even Medium Brexit, that could tip a weakening global economy into recession.  That would end Trump's hopes.