Signing Correa was huge. He gets to decide if he'll be back or not. It won't be the end of the world if he leaves but he's a needed presence in the lineup and on the field.
As GM/FO, you can't pin your team's hopes on rookies or mid-level free agents. Their success depends on several factors, some of which are controllable - pitching & hitting coaches, conditioning. The Twins have some things to think about with regards to those factors.
Athletes get injured. You can't predict that (although with Buxton, you can assume he'll be injured off and on) so you need a plan B at every position. The Twins have some OF depth but, as we have seen this season, not enough to sustain a team throughout a season. It's nice to have guys that can move around, like Arraez, Miranda and Gordon. All three are vital going forward.
I'd also like to see the Twins use some $$ to get a legit SP1 and a power hitter.