By the time the French Army defeated the rebels of Brabant, Prussia would certainly not be willing to accept Austria's rise in the Southern Netherlands and would thus have to divert some of its forces to support the Southern Netherlands.
Joseph had even prepared to create the appearance of the French Army running out of steam there, encouraging the Prussians to believe they might have another chance.
As the Prussian Army moved toward the Southern Netherlands, the troop strength in Silesia would inevitably decrease, and consequently, the pressure on the Austrian forces there would also lessen.
Feeling the supportive role that the battle in the Southern Netherlands played for operations in Silesia, Joseph II would definitely encourage the French Army to continue tying down the Prussians there.
At that time, the French Army's military presence in the Southern Netherlands would amount to de facto Austrian approval.
