The kind of turnover that would create would be brutal. Some exceptions would have to be made in terms of roster 5 guys, 8 guys I don't know what to make that system fan friendly in my opinion. Guys/Gals around here would love it because for the most part we have opinions on all players and follow hockey. Imagine explaining to your kid or a novice fan why their favorite players switch teams every three years.
I don't think the turnover would be as drastic as some fear. Most non-star players are already on 3-year or less contracts anyway. And star players typically want to stay with their team.
In the end, I don't care a whole lot. I would like to see a limit. And in general, the shorter the better.
I hate how much turn over the NFL has, I think this would be twice as bad. I just don't see enough positives. 5 year max? that would be low enough.
The NFL has a million other dynamics at play though. I don't think the two are very comparable. And I'd expect there to be less turnover in the NHL than in the NFL. I think there are more forces in hockey that compel guys to stay, in general, than there are in the NFL.