How much power, and hence his ability to effect change, will depend on the next round of elections in France. If he garners support in that election then he has the opportunity, along with the new German Chancellor, to mould European politics for a generation.
In the meantime we strike out on our own, time will tell who succeeds and who fails. One thing is for sure, there is no appetite in the UK to reverse Brexit. The protests have died out and at worse there remains a resigned resignation.
PS, I bet the EU parliament still ups sticks and moves to France every other month!