I think the team does improve, by a lot if they stay healthy -- however, enough to offset the loss of Correa? Possibly, but highly unlikely. Good teams often have good luck with injuries as well.
However, that is a LOT to ask -- because every team has injuries, and now this team has a lot of guys with injury history. And their biggest impact bat is lucky to play 100 games. I guess there is room for optimism if they stay healthy, but, again that is a big "if" and... they still needed to add a bonified ace, shortstop, and right handed power bat in free agency. In my opinion, they just don't have enough horses.
They NEED everyone to play at their peaks and have career years and health. Long odds. In order to do that, some of these guys need to rebound (Gallo, Kepler, Polanco, even Vazquez on offense, Pagan), have better health (Gray, Buxton, Kepler, Maeda, Ober, Alcala, Kiriloff, Mahle, Jeffers, ) and break out (Kiriloff, Garlick, Larnach) and continue to improve (Gordon, Miranda, Thielbar, Jax). And then young breakouts like Joe Ryan and Jhoan Duran and Miranda need to continue their high production.