As far as I can tell, this law has now gone into effect.
I don't care to go into excessive detail, but there is a thread over on utahconcealedcarry on this topic for any who are interested. But I do want to try to correct a couple of misconceptions about the bill.
First and foremost, the "holstered or encased" language does not automatically make a slung rifle a crime. The bill creates a safe harbor (check out the wikipedia article on "safe harbor" for more details) against disorderly conduct charges for a person whose firearm is carried either openly or concealed if the firearm is "holstered or encased". (How an encased gun might be openly carried is a bit beyond me, as is how a person carrying a concealed gun (including a pocket gun) might reasonably be charged with DoC, but not really relevant to this discussion.)
The creation of a safe harbor does not automatically create an "unsafe harbor". A gun that is not holstered or encased is not automatically cause for a DoC charge. To make such a charge stick, the regular elements of DoC would need to be proven. There are situations where the presence of a slung rifle might contribute to a DoC charge. There are other situations where a slung rifle would not be a material part of any claim of disorderly conduct.
The second area to discuss is why the "holstered or encased" language was even in the bill. It is there because after 5 years of trying to pass some protection against DoC for Openly Carried or Casually Concealed or even inadvertent display of a concealed firearm without this kind of a limit, we couldn't do it. Whatever one thinks of the prudence or propriety of carrying a slung rifle around a major urban area, two or three incidents that the media made sure were high profile had real effect on legislators. Whether it was just bad timing and bad luck, the anti-gun media exploiting to full value something that is fairly common, or some kind of agent provocateur I cannot say. But I do know that legislators could not be persuaded to give a carte blanche pass to walking around urban areas with a slung rifle.
So rather than go one more year with no progress on this issue, we went for a bill that provided specific protections for the way 99% of openly carried firearms are carried, without accepting any new restrictions on the 1% case. Two steps forward with zero steps backward is a winning strategy even if the goal is 100 steps away.
Under this bill, those who openly carry a holstered handgun should have strong protections against disorderly conduct charges.
Those who choose to carry a slung rifle will continue to need to evaluate the totality of the situation to determine whether they are at risk of a DoC charge. The bill (now law) has changed nothing in this regard.
I am not a lawyer and this isn't legal advice, but I'd expect the guy walking to or from the gun shop, or to or from a political rally, or at the rally with a slung rifle is unlikely to face DoC charges. The guy who loiters around a mall parking lot or who wanders around JC Penny with a gun on his shoulder or across his chest should probably be prepared for more scrutiny....just as he might have been prior to this law taking effect.
Charles