So, if he fumbles in games say--#5, #10, and #15 you don't believe that he'll still be getting chances?
He fumbled the exact same amount last year (4) as he did in 2012 when he ran for 1300 yds and 12 TDs.
The only thing that changed was the context of the fumbles, and the fact that he was on a shorter leash due to allowing 2 defensive scores when we were inside of the opposition's 30 yd line. Even after the Polamalu fumble in week 9 vs PIT, Belichick was still sticking up for him and saying that it's not just about one specific factor.
If he fumbles early on in the year, or has repeated weeks of fumbles = a stretch of a couple, then yes--things may be much worse for him. If not, he should be expected to get opportunities. After all, Belichick ended the year giving him opportunities, and he didn't fumble in the last 6 games. Let's not forget that RBs do fumble at times. It will be up to Ridley to keep those down to 2-3 sporadic times throughout the season if he expects to get chances.