The center will lead to the alt-right again.
Look at Bayrou who talk about "subversion migratoire", Darmanin telling lepen she's soft on imigrants or even Macron rolling the red carpet for the alt-right.
( Note : liberals are not leftist in Europe, they are center right, the left would be socialist )
Outside of France it's the same, liberals are all too happy to welcome fascist if it help protect the establishment.
In France we even have a saying for that : "Plutôt Hitler que les Front populaire" ( meaning people in power would prefer Nazi to a change in hierarchy, "Rather Hitler than the popular front" ).
All of that to say, don't hope centrist will do anything other than open the door when fascism come.
Alt-right is already declaring her a martyr and firing up their base. Even Russia chimed in, proclaiming European democracies as fake now. With absolutely zero self-awareness. Navalny-who?
Who with a working brain pays any attention to Russian talking points? They were flooding the zone with shit long before Bannon claimed credit for the idea.