France has always been an important player on political, military, economic, scientific, philosophical, religious, and artistic stages. Even though French predominance in one of these areas only lasted for some time (if at all), this country has upheld a very high level in all these areas practically throughout its history, the past 1100 years. Let me put these considerations like that: France is the most significant country in Europe on average.
It is easy to list factors which have contributed to France's favor in one or more aspects.
But as this is an AH forum, I would like to ask to converse question:
Which developments, roughly between 1400 and 1700, would have lead to a permanently weakened France?
Before you start posting:
No, I am not interested in any military disaster.
And I don't want France disappear as a state; the France of this ATL should still exist and hold, say, 80% of all French speakers.
Sorry, Angevin-Burgundy conspiracies not welcome.
And I do understand that a big meteor dropping on Massif Central or a disease stopped by effective French custom officers would do harm to France.
I find such violent PoDs boring (for the most part).
Just observe the contrary: France didn't join the prime league because of Napoleon's conquests, but Napoleon's campaigns were (among other factors) allowed for by France's excellent general condition.
So what I am really looking for is some silent, slow process which doesn't ruin or destroy France, but gradually and irresistably takes France to the B ranks.
Any thoughts?