@adamhjk I think I disagree with you here and see the advantage of making normal attributes non-persistence, because I've seen that bite people.  I'll also bet that the major of the use of normal attributes is currently 'incorrect' and that the users don't understand that they're getting persistence.  The ones who do understand that they're getting persistence are also going to be capable of understanding the problem and migrating.  We should also consider trying to produce a gem like 'transpec' to auto-upgrade cookbooks (and retroactively fill it out with Chef 10 to Chef 11 auto-migration).  Also, correct use of normal attributes is less common -- this should not change every cookbook on the planet.

I do agree with you later where the impact of changing node[:fqdn] to sys[:fqdn] touches too many cookbooks and doesn't have enough of a payoff to warrant it.