Good problems to have - 2. The bullpen, in general
There's still speculation the team could add another reliever, such as Ryne Stanek, which gives the Cubs a solid bullpen but, consequently, leaves good pitchers off the major league roster. The bullpen, now without Stanek, could look like:
Javier Assad
Drew Smyly
Jose Cuas
Luke Little
Mark Leiter Jr.
Julian Merryweather
Albert Alzolay
Hector Neris
This effectively leaves Daniel Palencia, Hayden Wesneski, and Carl Edward's Jr. with a steep uphill battle to climb to Texas with the team's 26-man Opening Day roster. You could also swap out Cuas or Little, who still have minor-league options. The point here is that this is an exciting situation before adding another arm like Stanek. From there, the Cubs bullpen and almost an entire backup group of pitchers in Iowa are stacked.
In the end, Hoyer is all about depth, and if he can land another arm like Stanek, he will in a heartbeat. The solution is to send one of your younger guys with options, most likely Cuas or Little, back to Iowa to be ready to be called upon when needed, as opposed to having both on the MLB roster to start the year. As with the lineup, you want to refrain from banking on prospect production to be the team's primary source of success. Thankfully, the bullpen is the most straightforward "good problem" for the team to figure out.