The reality is that even if we were to lose one of our non-Rondo guards to a season ending injury, we'd still be OK without even having to rely on a Joseph, Christmas, or Smith. Just by taking everyone's averages from last season, we can see this:
Rondo 37/Terry 13
Lee 31/Terry 18
And that covers all the 1 and 2 minutes keeping everyone at least year's averages without even touching the rookies.
And if we wanted to lower Terry's minutes, we could slide Pierce to the 2 for 5-10 mpg to give Green more time at the 3 spot (and consequently open more minutes for Sully at the 4). Pierce may be slowing down, but I have no doubt that he could at least hang with the backup 2s of the league.
So while I would've preferred Dooling to stick around for leadership and extra insurance, even without Bradley (or if Lee or Terry went down once Bradley is back), we're still in a pretty good place. Worst case scenario, one of the rookies has to play the odd few minutes here or there in the regular season.