The health of the French economy is somewhat disconnected from the fiscal health of the French state, the latter being continuously prevented by the parlements (esp. the Paris parlement) from raising taxes on the aristocracy + clergy, as well as engaging in any meaningful reform of the tax-farming system, or the tax system in general.
France was already in pretty dire financial straits even before the American Revolution, with war debts reaching back to Louis XIV and Turgot already proposing serious government cuts in the mid-1770s. Financial wizardry such as proposed by Necker (tinkering with the accounts in the Compte rendu in order to boost confidence) would have disguised the issue only temporarily, even accounting for the exceptional OTL ARW expenditure.
Eeventually the unreformed state would have run out of creditors willing to lend it money. The resultant bankruptcies of the state, the creditors/banks, and middle-class bondholders, as well as the loss of faith in state institutions, would doubtlessly have had severe repercussions on the French economy.