I doubt that Prussia-Brandenburg will completely be wiped off the map, however it will have a few territorial losses. First of all the Austrian Habsburgs will regain Silesia.
Perhaps Saxony will be rewarded with some territories too, maybe Magdeburg.
More importantly Prussia-Brandenburg will no longer be one of the dominant powers in the region, but it will be demoted.
Instead Austria, Russia and Poland-Saxony will be dominant powers.
In a more extreme and far less likely scenario Poland regains the territory of ducal Prussia, which will reduce the Hohenzollerns to their territories in the HRE as elector of Brandenburg (king in Prussia probably will be used in pretence, though without real recognition).
Such a scenario will make Austria the unchallenged dominant force in the HRE and will make an unification of 'Germany' by Austria more likely. OTOH eventually an other protestant German state could take over the role of Brandenburg-Prussia, or maybe even ATL Brandenburg will slowly be able to recover.