Notes:

NOTE: I know that the head is different and this probably isn't anything, and that's why I didn't say this was a theory, It's just a little observation that these two look similar that I happened to notice when I saw FNAF3's trailer. I don't actually think that Golden Bonnie is connected to Shadow Bonnie in any meaningful way, it's just something I noticed and thought I would share with people.

TL:DR- I know this is probably not anything substantial, so don't yell at me for being wrong. It was just an observation I made.