If Mack messes up and ends up getting benched, then yes that opens a lot of opportunity for Wilkins and Hines to take advantage of.
If Luck is back healthy, this could be a very good offense, and so valuable touches for the RB even if the RB are not that special or long term starters for them.
It could be RBBC all year, or it could be split up during the season, for example Mack getting 50% of the rushing attempts for the first 4-6 weeks then maybe Wilkins gets those touches later on in the season if Mack gets benched or injured.
I don't really see Hines winning the starting job. I just think he will be involved as a 3rd down guy or on certain plays and that is what he does, regardless of what the RB are doing.
So if you invest in Wilkins, I see it as a play for this season and hope he does have some big games along the way.
I do not see Wilkins as a long term answer (maybe I am wrong) who would be able to earn the start and hang on to it for several years, which is what I thought of when you compare him to Forte.
I think WIlkins is okay but not as good as Forte. Looks like a journeyman type or career back up more than a starter in my opinion.