Triple Frontier is a film that could very easily lend itself to a sequel, and that sequel could be really good.
The result of this whole exercise is a pro sequel outcome, so long as those involved keep their heads on straight during development.
In fact, bringing in J.C. Chandor and Mark Boal would be required at this point, as Chandor knows the characters and Boal knows how to bring the action.
But, even with the ideas presented, there’s a risk that such a sequel would be a really bad idea.