I'd only weep for studios that bring something unique and cannot be replaced easily. The only studio that comes to mind is Square Enix, because they're the only ones willing to create AAA JRPGs on a regular basis. Wouldn't weep a tear for anyone else. (well, maybe Psyonix)
Bandai Namco? Their output isn't as huge as Square Enix, but they are the publishers for Tales and Ni no Kuni, as well as some smaller franchises.
I'd probably be most upset if they disappeared, since they support some really weird series like Katamari. Capcom would be up there, too.