The entire western market isn't going to simultaneously and instantly stop eating meat. There won't suddenly be a day when all the herds are culled because everyone finally stopped eating meat at once. If it ever happens (I'm hopeful but not optimistic), it will be a gradual process, and industries will have lots of time to adapt.
But even that aside, it's not our duty as consumers to keep eating animals to keep industry able to make shoes and cheese.
My point is, what are we going to replace those with? Especially leather & co. They have real life applications, they're not just fads. Plus, will those replacement products be sustainable? Vegan leather is just rebranded plastic, for example.
I'm equally curious, but I don't know the numbers, if replacing plastic packaging with paper/cardboard is environmentally sound. I remember back in the day efforts to reduce paper consumption, I think our sustainable paper production capacity was near its limits.
Cactus leather is a new trend. I don't own any cactus leather products so I can't say how good it is, but surely it's possible to replace cowhide with something.
Even vegan (plastic) leather is significantly better from an environmental and emissions perspective than cowhide leather. The tanning process is not exactly eco-friendly, and neither is raising cows.
But even that aside, it's not our duty as consumers to keep eating animals to keep industry able to make shoes and cheese.