A DMs dilemma - to let the party loiter or not?

[DMThac0]

Your players are monsters who are reaching a turning point in their escapades and have made a plan of action after they achieve their current goal.

You are no longer in control. I said it, I mean it, and I thinks it's the best thing in the world for your adventure now. Stop building the adventure for them, build the adventure because of them. Ask them what they're doing, and figure out how the world is responding to it. Hopefully you've taken note of their antics up to this point. You have ammunition there to create the opposition for your players. Did they leave a trail of death and destruction but a young man and his friend survived? Hey, that sounds like the back story of one of my players from the other game I used to play.... You now get to play the heroes instead of the monsters, shift roles and have fun.

I do have one question which is extremely important right now: What are your success and failure states? If they "win" what happens? If they "fail" are the players headed for a tpk?

With that answer well defined, you should also be able to create responses to your players which is appropriate as well.