There would be no issue for 2014, as he'd likely go to AA or AAA like Drew did until rosters expand and even if not Betts could go back down.
For 2015 you've got all winter to evaluate Vic and Craig and explore trades of Middlebrooks (making holt the 3bman), Nava, JBJ or even Betts. If everyone is back and healthy, and Castillo wins the CF job, then JBJ and Betts go to AAA, the outfield is Craig, Castillo, and Cespedes, with Vic as the 4th outfielder, Holt as the backup infielder (unless he's starting at 3B with Middlebrooks backing up) and Nava a 5th outfielder, backup 1st (the Carp role).
In 2016, Vic and Cespedes, and Napoli could be gone making way for Betts and JBJ, with Craig moving to 1B. Or you sign one of Napoli or Cespedes, making JBJ or Betts the 4th outfielder and the other a starter.
For 2015 you've got all winter to evaluate Vic and Craig and explore trades of Middlebrooks (making holt the 3bman), Nava, JBJ or even Betts. If everyone is back and healthy, and Castillo wins the CF job, then JBJ and Betts go to AAA, the outfield is Craig, Castillo, and Cespedes, with Vic as the 4th outfielder, Holt as the backup infielder (unless he's starting at 3B with Middlebrooks backing up) and Nava a 5th outfielder, backup 1st (the Carp role).
In 2016, Vic and Cespedes, and Napoli could be gone making way for Betts and JBJ, with Craig moving to 1B. Or you sign one of Napoli or Cespedes, making JBJ or Betts the 4th outfielder and the other a starter.