Imagine this. The Sith Fleet is fractured, and flees when they see the mighty Star Forge destroyed. They had no leader, nor plans. Yet the Republic fleet was decimated, with many of the Jedi dying either aboard those ships, or dying aboard the Star Forge.
Many planets still have Sith governments, and the Sith have more ships. The Republic won this battle, but face the thread of further Sith expansion regardless, and now very few Jedi survived to aid in the coming battles.
Saul's second in command assumes control of the Sith fleet and orders the fleet to move in on Coruscant, and then the credits roll.