You guys will be fine without Richardson. Holmgren is and was past his prime like 7 years ago. The Colts are not a dynamic team even with Luck. They go 9-7 at best this year. But my prediction for the colts is more 7-9.
The biggest reason the Colts were so successful in the 2000's was because of a man named Bill Polian. Who also so happened to be the bills GM when the Bills went to four straight superbowls in the 90's. Jim Irsay and his staff are bumbling bafoons and they go after whatever player is "Extremely Hyped".
The only thing I think holding you guys back at this point in time is having Lambardi in your FO. He hurt the Raiders big time when he was with them. And the fans still hate him for it.