If this can help poaching of rare animals I hope they can find angel investors with money who care about saving wildlife-great idea. Can they make horn materials like Rhino and Elephant?

Fantastic idea, so the whole world eventually stops killing animals but their feeding demands will still need to be met and while they continue to breed out of control they would soon be consuming everything that can be grown. Of course we could introduce regular culling to keep the numbers down but wouldn't that defeat the object ?

HA, this immediately made me think of the artificial vat-grown meat, Bison-Boar from John Scalzi's book the Android's Dream.
"...And when they did eat meat, they picked out a tube of vatted meat product, made from cultivated tissue that never required the butchering of an animal, or even the participation of any sort of animal outside of the purely mythical. The best selling vetted meat product on the market was something called Kingston's Bison Boar™, some godforsaken agglomeration of bovine and pig genes stretched across a cartilaginous scaffolding and immersed in a nutrient broth until it grew into something that was meatlike without being meaty, paler than veal, lean as a lizard and so animal friendly that even strict vegetarians didn't mind tucking in a Bison Boar Burger™ or two when the mood struck them. Kingston's corporate mascot was a pig with a bison shag and horns, frying up burgers on a hibachi, winking at the customer in third-quarter profile, licking its lips in anticipation of devouring its own fictional flesh. The thing was damned creepy." (John Scalzi - "The Android's Dream"

Craig, that's just bad MARKETING on Bison Boar Burger's part. Anyway, you DON'T have to EAT it, there are other uses as well & if Bison Boar is creepy, what do you think about eating something that was REALLY once alive?

So if we eliminate the need for the millions of animals used for meat and leather now; what becomes of them?

Why, Robert, they'll be slaughtered of course. The corpses dumped in a landfill to rot.
Humans are omnivores. Livestock aren't pets.
To anyone who is both religious and vegetarian, I say Genesis 1:21.

The animals eat all of our fruits and veggies, and we all end up dying of malnutrition anyway...

until vat meat is a reality, leather is mostly just a byproduct of the meat industry. Cow goes in, hamgurgers, steaks and nice shoes come out.

re; Gregg Eshelman
Genesis 9:3 Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things.
The bible does not encourage vegetarianism nor does it require the consumption of meat.

I fail to see what a book of middle-eastern fairy tales has to do with biotechnology.