Given that out of the dozen or so "main political parties" he is the only one who wants that, and that when asked about their priorities for the change of France no group of frenchmen put that in their top 5 besides voters of LFI ...
You're absolutely right that there are definitely some people who want a 6th republic but do not vote or agree with LFI, but for the sake of generalized conversation like we're having now they're mostly irrelevant. If it were to happen, it would be through him and his "vision", and as such I maintain my critics.
Beware of what you want for you might just get it.