Your hypothetical depends on a number of situations. Do we have meat replacement? Is it illegal? Is it just not available anymore?
If we have a meat shortage, it's illegal or just isn't available anymore, I think I'd just eat whatever I could find. I wouldn't resort to killing animals. As long as stores still exist and other food is available, I'd eat whatever left is available. If I lived in the woods/wilderness and there were no stores at all though, you pretty much have to hunt and eat meat. You can't grow vegetables year round and can only store so much.
I enjoy the taste of meat but I have zero problem not eating it if we got to a point to where there were healthy, cheap and abundant options to replace it. If we can make meat in a lab and it's proven safe, tastes good and is a suitable replacement, I'd all for it. I do have a moral dilemma with eating meat and I don't like the idea of factory farming. I see it a necessary consumption right now though.