Hi Priscila! It sounds like a good scenario to work with shared models to me, as they will need to make decisions as a team. Something that sounds appealing to me is working on the skills they will need to actually overcome their crisis first, and then working on what could be their plan for the future. Both plans have in common one question: what do they need to keep and develop (and why), and what do they need to drop (and why).
A good pre-workshop session with their leaders would be a good idea, so you can extract a few desired outcomes from them. From the description you shared, it does look like they are going through a crisis and need to figure out how to overcome it, so I would start with getting a clear direction from them. Do they want to understand why they are failing? do they want to innovate? are they thinking about changing the team culture? is it really about planning, or sales? All those questions usually help!
I like your idea about having them create different scenarios. As a follow-up to that, I’d ask them to build something together with what they identify as the core of each model and see if there’s consensus around a potential “best” scenario in that case.
hope that helped!