It's not *quite* as bad as your title suggests. On private property (e.g. Center Stage), the owner can refuse admittance to someone carrying. The difference now is in the default -- under the new law, absent specific instructions by the property owner, customers can bring in guns. Under the prior law, customers needed prior approval to bring in a licensed firearm.
I don't expect big changes at venues that already had security in place. Other places (churches, schools, stores, taverns), there's more likely to be some ... consequences to this change.