In principle, I am for this change. (I don't like the removal of calories from fat, but that is another matter.)
In practice, it's (worse than, arguably) useless. Because: How do you define added sugar? Is adding concentrated grape juice, for example, considered "added sugar"? Dehydrated apples? Sorghum syrup? Corn syrup? High-fructose corn syrup?
No matter how you define added sugar you'll both end up pushing people away from "good" products, and not pushing them away from many of the products that this is intended to push people away from. The large businesses have the money and the reasons to try to find alternatives that are not classified as added sugar. They'd find alternatives that are essentially equivalent but are not classified as such. Whereas smaller businesses will not be able to. Speaking in generalities here, but that is what I'll predict will happen if/when this change goes through.