It's easier to look at the facts, see Romo's results, his record as a starter, his career stats and the position he puts this team week in and week out, than to find a capable replacement.
Romo is a top 5 QB in the league in my opinion. Brady, Brees, Manning, Rodgers (the other four). Are you seriously saying you can find a QB that's better than any of those guys? Good luck finding him and going back the the mediority of the 2000s. Clint Stoerner, Drew Henson, Quincy Carter, Tony Banks, I'm sure they're all a fun and cool bunch, but Romo is at an entirely different level than everybody else.
This team without Romo would be the Buccaneers, Dolphins or current day Vikings. Talented, without any quality QB that can win more games.