If Dallas has lost their former pro bowl guard, it is difficult to imagine the OL providing even average pass or run blocking. If that is the case there will be plenty of 3 and outs repeatedly putting a thin defense on the field and opening the door to a lot of yards being surrendered.
On top of that, fans are putting pressure on Garrett to open up the offense.
Garrett has to do what he can to keep Romo on the field. If Romo goes down this team could finish the season 0-8. Any scenario that has this team finishing outside of the playoffs will enrage the fan base and lead to a Jerry Jones snap judgement designed to correct "the problem".
Put another way, it could cost Jason Garrett his job. That means shorter pass routes.
Now on the positive side, one has little doubt that while the team will be launching quick passes, a much greater percentage of them will be aimed at Dez Bryant, regardless of double coverage. That should help the offense.
Additionally Demarco Murray's return should help the offense immensely, somewhat offsetting the loss of Waters. Murray is a solid pass blocker, a good receiver, and an above average runner who really suits this offense. It is not a coincidence that the offense looked great when he was playing and lousy when he wasn't. He does a LOT for this team that his backups cannot (yet).
I hope the team goes 9-7, but given that Jerry Jones doesn't understand the need for building around durable starters or, barring that, the need for quality depth, this team is built for 8-8 annually.
I think as long as Garrett makes the playoffs and they are competitive in the first round, he is safe. Jerry Jones really likes having a very solid head coach who likes Jones and even will tolerate Jones's meddling.
I personally think Garrett is a fine head coach who would do far better elsewhere. If Garrett is Fired, I think former Dallas DC Mike Zimmer would be willing to step in with largely the same staff and would be able to build off Garrett's foundation. Zimmer also has very fond feelings for Jerry and would likely work well with Jones.
Any Cowboys fan hopes for a super bowl every year, but the reality is until this team builds a good OL with solid depth, that isn't a possibility.
I'd like to see Dallas go 4-4 the rest of the way and win the division at 8-8, but to be honest a part of me perversely hopes Dallas wins the division at 6-10. But I would like to see them win the division.