This is a tough question to answer. We don't know what will happen with TO and Glenn (he plays better with BP). We don't know how our OL will shape up (we have 3 UFAs). We don't know how good Garrett will be.
If we go at least status quo, then I think Romo will have another solid year. I can see him throwing for 3200+ yards, 20+ TDs, and 15 or so INTs. I saw enough from Romo this year, to be cautiously optimistic. I'm not sold, as many are, that he is the next Joe Montana. I'm also not sold, as many here are, that he's the next Quincy Carter.
If we can shore up the OL, and Garrett is as good as advertised, then he'll be poised for another Pro-Bowl.
On the other hand, if we still have questions on the OL, then I think Romo may be hearing the boo birds early.