Negan will assume Daryl is wherever Rick is. After the events in this episode, I would expect what's her face to break her promise and reveal where a large gun stash is.
They are going to have to find a way to stall Negan.
If they want to defeat him, I would do the following:
I'm going to assume Negan has close to two thousand "Saviours", maybe less, based on Michonne's comments (a guess). So a direct assault would be foolish. I would also plan on (but think the probability low) a Negan assassination to trigger an attact by the Saviours. So first banish any children and pregnant women from the three encampments.
Next, trick Negan into another personal visit. Slaughter the entire visiting party, except for one (preferably a minor player). Return him with Negan's body to his hideout so it's clear they are no longer enslaved. Then brace themselves.
True, they might be attacked, maybe even destroyed (I would argue they are already destroyed. Sneeze wrong and Negan might kill someone.) but ANY aggression toward Negan would be met the same. At least this way Negan would be out of the picture.
On another note, if they made a bullet, does that not mean they have gun powder? And Negan didn't want to see where this bullet was made??
What was up in that scene after the credits?