There would probably be some changes to this treaty to make it more acceptable to 3+% of French voters and then a new referendum on this treaty might very well be held in France.What if the 1992 Treaty was rejected by the French population by a 53 - 47 margin instead of the OTL acceptance of 51-49%. How would this affect the European project and continental politics?
It would continue onwards as though nothing had happened. The elites would ignore the result or force the French to vote again and again until they voted the way they were supposed to. See also the referendum on Ireland joining the Euro and other referendums which went against the Brussels fascists and were reran. See also the attitude of the likes of Peter Mandelson when questioned about how one of the referenda went to see what the attitudes would have been. The turkeys aren't allowed to vote against Xmas.