Makes for some intriguing possibilities.
In my view, they can't actually let the entire Grimes Gang go bad, so I assume that if they do take the town, it'll be because they were forced to because:
a) it's some sort of trap that Deanna is unveiling.
b) some of Deanna's people go rogue.
c) some of the Grimes gang go rogue.
The last seems unlikely to me unless it's a weaker character giving into something (e.g. Gabriel). The middle seems very likely (Aiden and the stylist's husband have been set up as potential menaces), and perhaps it could be a case of a few members of each side staging some sort of coup.
The danger being a trap orchestrated by Deanna seems less likely to me, since it would be too much of a repeat of Terminus. But that doesn't mean she can't be an opponent. Maybe the trap is to manipulate them into fighting a third rival.
All speculation, of course. They managed to stay on Herschel's farm for like 1000 years with only a major interpersonal conflict and one run-in with another group...
