The Astros are taking some lumps this year, and we're seeing that the future has not yet arrived. But one thing I have found impressive is the depth the Astros have accumulated. Here are the likely fill-ins at each position if there were an injury, trade, or demotion:
C - Cody Clark or Jason Jamarillo. Either of these guys would do OK as a backup (though Jamarillo has looked bad at the plate so far at OKC). Jason Castro is perhaps the most irreplaceable guy on the team though. Corporan/Clark is a serious drop-off from Castro/Corporan.
1B or 3B - Brandon Laird. Laird doesn't walk much, but he brings solid power and defense to the table. He would probably start at 3B if Dominguez went down. With Pena, Wallace, and Carter all possible first basemen, Laird would be a backup at that position if he were needed.
2B or SS - Jake Elmore. Elmore is off to a great start so far. He is no Altuve, but he could provide solid play at 2B in Altuve's absence. Because defense at SS is not a strength, he would be a backup SS if one of our two main SS's went down. A healthy Jose Martinez is another viable option. Jon Villar does not appear to be ready anytime soon.
CF - We have enough potential CF's on the major league roster (Maxwell, Barnes, Ankiel) that we might not need to call on Che-Hsuan Lin if a CF became unavailable. If Lin were called up, it would definitely be in a backup/pinch-running/defensive replacement role.
RF or LF - Fernando Martinez - he is due for a call up soon anyway, once he finishes his rehabilitation. If he replaces J. D. Martinez, J.D., Robbie Grossman, Marc Krauss, and Trevor Crowe would be available. Some good options here. As a good prospect, Grossman would be the interesting choice, but J.D. and Crowe are more major-league tested.
SP - Jordan Lyles. This one is tricky. Jarred Cosart is off to a good start, but service time considerations may come into play for him. Rudy Owens is a possibility too. But Lyles would probably get the call if management was convinced that he had worked out the issues he was having in spring training. If Lyles could return to his usual form, he would be adequate as a replacement. Clemens or Keuchel could also be transitioned to a starting role in a pinch.
Conclusions - The Astros have a good replacement team waiting in the wings. Though it would be great if we avoided injuries from here on out, if injuries, trades, or demotions do surface, the Astros have decent go-to guys in the regulars' absence. The switch at starting catcher would be the most significant drop-off.