If we're being honest, every team's worst-case scenario has to be the same--the team plane going down. That's literally the last thing we'd want to see happen.
Aside from the team getting wiped off the face of the earth, my most realistic worst-case scenario has to be getting off to an equally horrible start in 2017. This team, more than any other in baseball, can't afford another 0-9 start. The Twins haven't won a season opener since 2008. Wouldn't it be huge for this young team to get out of the gates hot and start respectably, even going 6-3 to start? An 0-9 start would once again cause these young hitters to press at the plate and fall into prolonged slumps leading to a 14-37 record through May, killing what remains of fan enthusiasm and hope.
Obviously, the young players failing to develop and starting pitching failing to take another step forward would be crippling as well. But for me, the season could be defined by the first 9 games.