I'll concede that this scenario is shaky as hell but it might work, the PoD being that Charles XII is not wounded in the foot before the Battle of Poltava.
The morning of July 8, 1709 finds Charles XII of two minds, on the one hand he's in hostile territory, effectively out of supplies and backed up only by Ivan Mazepa's unreliable Cossacks. On the other hand his army is still undefeated and if he's lucky enough (which he usually is) this could be the final decisive battle of the war.
By day's end it looks like Charles's luck has won out again, the Russian army is routed and as the icing on the cake, Peter the Great is killed as he attempts to withdraw over the Vorskla. Russia falls apart effectively overnight. Mazepa has proven his is the horse to back and many Cossacks join him in rebelling from Russia. At the same time the Russian government collapses into infighting with no clear line of succession. The worst damage however is the loss of Peter's reforms; without a strong Czar to keep them in place Peter's unpopular modernizing reforms are thrown out, keeping Russia a backwater for decades to come.
But Charles flush from a resounding success in the Great Northern War and headstrong as ever isn't done with his military adventures. In 1710, in a move unexpected, though long feared by certain parties in Europe, Charles intervenes in the War of Spanish Succession. Charles's motives are honestly fairly weak, some vague points about helping old allies in France and keeping those dastardly Hapsburgs away from Swedish possessions, but that doesn't stop him. The war is already winding down and there aren't many opportunities for battle left: the British need Swedish naval supplies and large amounts of Dutch wealth comes from Baltic trade so neither of the maritime powers actually desires to fight Sweden. Likewise Austria is too far south and too preoccupied with France to really do anything to Sweden. With few opponents, Charles manages to win only a few token victories in Northern Germany before the war ends.
The important gain however is that Swedish dominance is recognized over the Baltic and Northern Germany. Between the War of Spanish Succession and the Great Northern War Sweden has managed to secure itself a corner position geographically in Europe and a solid sphere of influence that can't be seriously disputed except perhaps by the Hapburgs.
I'm not entirely sure where this would go, but this set up, unlikely as it may be, gives Sweden a solid shot to ride out any major wars in Europe down the line, as well as a burgeoning resource and manpower base in Germany and fractured Russia to fuel industrialization. So in another couple centuries from this scenario, Sweden might still be counted as one of the great powers of Europe.