Too early to tell, since the new guy isn’t in the position yet. But I think there are some guesses:
1) ISIS terrorists are going to try and hit France again to make Macron’s life more challenging.
2) Macron is going to ally with Merkel and make Brexit even more difficult for Britain (which, by the way, Britain deserves)
3) He’s going to have a challenge getting stuff done in the Assemblee Nationale, since he doesn’t have a strong political party to back him up.
4) He and Trudeau (Canadian PM) are going to go surfing together.