How will the Colts split backfield work?

Indianapolis Colts running back Ahmad Bradshaw was placed on injured reserve yesterday and is set to undergo season-ending neck surgery. Last week we discussed the state of Indianapolis' backfield if Bradshaw was out for the season, positing that Trent Richardson will likely transition into a full-time workhorse instead of operating in a quasi-timeshare. Now that Bradshaw has indeed been ruled out for the year, we'll find out out how big Richardson's role can become and if backup Donald Brown will continue to step up.