NO.
The Union could have stopped fighting but in no military sense could the Confederacy win the war.
The anaconda strategy worked.
Yes, Anaconda worked.
But only because of the continued, and expanded, political will in the North to win.
Recall, for instance, that during the Battle of Gettysburg there were major draft riots in New York. And Lincoln had the Copperheads to contend with.
Had Lee won at Gettysburg, or avoided it entirely and successfully moved on Harrisburg and/or defeated the Army of the Potomac in detail, the pressure on Lincoln to negotiate a settlement would have been enormous. Had the 1864 election taken place with either a stalemate or the Union armies attrited (as opposed to maneuvering ever-forward as the twin victories at Gettysburg and Vicksburg enabled), Lincoln probably would have lost to Little Mac, who would have negotiated a settlement.