It may very well depend on how fast they think they need to start the season. Lets suppose a few teams get into the loop and snatch up two of the starters like Lester and Scherzer.
That would leave Shields, and some lessers like maybe Santana, Liriano, Hammel. Lets suppose they take Shields and also go for Bret Anderson or Liriano as middle strength leaving Wada and Hendricks at the bottom barring injuries.
Bryant doesn't figure to be up with the Cubs for a few weeks, and like I said, the youth will still be going through rough patches which will probably include Bryant too. Not saying that a few may surprise, but for arguments sake, lets say they do.
Now, if the Cubs are remotely close to .500 near the deadline plus or minus, and some players have indeed found their strides, the Cubs may at that point pursue a trade to land a Hamels, Cueto, Latos, Gray, or any team that may be out of the hunt. The Cubs may also not have to give up as much lets say, if someone like Baez (example) turns the corner a little while Addison Russell gets ever so close to the majors. The Cubs then hold the cards.
This also allows the Cubs to have the first three months to evaluate, and possibly strike it with a team that may be in fear of losing their pitcher to free agency.
I feel the Cubs will be buyers at the deadline this year regardless, as they may position themselves before the next off-season, and not have to deal so much with free agency and trying to land the pitcher they feel moves the team forward. Just my opinion.
Of course, landing any of the big two makes anything I said pointless except for possibly still being buyers at the deadline.