And they'll replace their meat with what? More sugar? Bread? Sugary bread? I think you underestimate how big of a deal food is to people. I believe that any change will be towards food that's even worse for people.
Hopefully with less food in this theoretical scenario because most people are overweight.
For many people, those calories doesn't need to be replaced with anything.
Why would people replace meat with sugar?
Because of how much of it is added into every alternative meat replacement product, and it's a shockingly high amount if you read the labels on some "organic" and "plant-based" products.
I have a few issues with this. As far as I know health concerns related to meat replacements aren't to do with sugar levels, probably more likely with saturated fat and sodium (which exists in regular meat too). Also I don't know why you bothered to put organic in there as well since the we're talking about meat replacement. Finally I think you're making the assumption that if we don't eat meat we need meat replacements at all.