I don't think the French establishment will allow that to happen. Either Le Pen's opposition will unite, or the ballots will be rigged, or Le Pen will get caught up in a phony scandal.
There is a fourth possibility. Well, let's just say that Le Pen shouldn't take any long walks by herself.
I'm betting on Door #3. The united opposition is a longer shot and rigging ballots there takes real work. The French have been smart in avoiding "modernization" of their electoral system - electronic voting has not been adopted on a large scale.