Well last year, being his rookie season, it was anticipated that he'd be a little tired, especially with carrying the load the first 6 games. It was good that we were able to rest him with RW...so, no he'll have a year under him and the rigors and grind of a full season will not be an issue. He'll have learned how to keep his body from getting tired thru offseason conditioning. He won't hit the rookie wall a second year...
As to missing RW, while I think not having him can't be as good for RB and the Fins as having him, I don't think the season is in jeopardy at all. S. Morris and KJ Harris will have the fill-in work to keep Brown going.
I still suspect that IF he gets off on the suspension, a draft day or just before draft day trade isn't out of the question. I think if the Colts want to stay somewhere near where they are offensively, they have to be interested...I also believe Shanahan would still be interested as well.