As will be apparent, France's electoral system is geared at preventing shock change and powerful leaders. Remember that the French bourgeois virtues include médiocrité, which means something a little different there to our jibe of mediocrity. And having soundly rejected the 'constitutional' parties of right and left for the Presidential election, French voters may not have the same choice for the two-stage Assembly elections on the 11th and 18th of June. Well-oiled local Republican and Socialist party machines may cement support, leaving Macron a lame duck President with no support in the Assembly.
And yes, short of some earthquake shock, Macron will be France's next president.
Marine Le Pen is not finished - France and Britain will both go to the polls again in 2022, and in political terms that's an eon away. As for what this all means for Brexit, I'll guess little change. The Kermits still hate us and want us to suffer because we're so much more successful than they are, yet we need to co-operate even more closely militarily as the only two armed nations in Europe. It's all French toast - brittle with burnt crumbs. Hey ho.