The rule will be that weapons can be openly carried in the NP and concealed weapons can be carried with a permit, but this only applies to the land of the NP. You can not carrry a weapon in any government facility, meaning the visitors centers, office, mountain guide center, etc. You can carry a weapon in the Paradise Inn and the Longmire Inn, unless prohibited by the concessionaire.
But all this has a catch.
It is still illegal to unholster a weapon and use it, even in the defense of life and property or discharge it in the backcountry (hunting is illegal in the NP).
In addition, from now on, all rangers will approach and treat people in the NP as if they have a weapon. This has been the training and the approach sometimes but now it will be the basic rule. So, when a ranger approaches you, try to show you don't have a weapon and are not a threat to them or others.
I still hope Congress will overturn this law. It wasn't necessary and only endangers all the people in the NP as well as hinders the appreciation of the NP and people's experience. Everyone will have to equally be wary of others if it's possible they could be carrying a concealed weapon and especially if they're openly carrying a weapon.
Personally, you can bet I won't trust anyone beyond what I can see. As a photographer, carrying my camera equipment in the backcountry, I won't trust anyone who may have a weapon and can threaten or immidate me, or worse rob or injury me. This law makes the NP experience worse, not just everyone, but more so foreign visitors who could have a bad experience.
So, I still say, keep you gun at home. It's unnecessary and needlessly endangers others. The right to carry a weapon doesn't make it right to do so. Please respect others.