"I know a lot of the guys in here know there is a good chance that everyone is not going to be back," Zimmerman said. "If it was up to us, obviously, we want everyone to come back, but that's not how the business works.
"I think [the front office] has a done a really good job of drafting and getting guys up to take [their] place. I think whether it's all of them, none of them or some of them, I think we are going to be good for a long time no matter what."
It wouldn't come as a surprise to see right-hander Lucas Giolito, infielder Wilmer Difo and shortstop Trea Turner get a chance in the big leagues by next year.
Giolito is the No. 1 prospect in the Nationals' farm system, according to MLB.com. He spent all of last season with Class A Hagerstown, going 10-2 with a 2.20 ERA. He is in Florida and involved in a throwing program under the team's supervision.
Difo, who will start the season with Class A Potomac, is coming off his best season for Class A Hagerstown, hitting .315 with 14 home runs and 90 RBIs. He can play shortstop and second base. Difo is Washington's No. 8 prospect, according to MLB.com.
Turner, who is expected to eventually play shortstop, remains in the Padres' organization and will start the season with Double A San Antonio, according to the San Diego Union-Tribune. Turner will join the Nationals after the First-Year Player Draft in June.