And there's vegan cheese https://www.reddit.com/r/vegancheesemaking
and of course vegan yogurt etc. (you can make yogurt with coconut milk for example)
...and it sucks as a replacement for genuine leather.
My old boss was vegan (or rather his wife was and he was very accommodating of her diet, he would still eat meat outside the home). He would always mention that the fanciest, most expensive vegan cheese option out there set itself apart from the rest with the tagline "It melts!" on the packaging. Vegan cheese has to come a long way to be anywhere comparable to real cheese. The same applies to synthetic leather, by the way.
But if you are looking for something like a slice of cheddar or vegan mac-n-cheese the options are really pretty terrible and all have an aftertaste like you just ate a spoonful of Crisco.
[0] https://miyokos.com/products/classic-double-cream-chive-chee...
I don't think I have ever seen something trying to imitate any really soft (brie) or blue (roquefort) cheeses.
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.
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.
You forget all that leather used in a myriad of products, that leather comes from cows. Or feathers and down from various birds. Or the other million side products of animal husbandry, that I'm not even aware of. I think almost every part of a cow is used in an industrial process, not much is wasted.
Plus, this needs a totally vegan solution and you're wiping out any and all dairy products: cheeses (all 100 million of them), yogurt, regular milk, sour milk, sour cream, whey, etc.