Nothing. Not today at least.
The unlikely but noteworthy situation is in the realm of 'doxxing.'
Tying a public online account to a picture of your face allows someone with moderate to advanced knowledge and IT literacy to find pretty much all of your other online accounts, social security number, address, family info, etc. in 2018.
Someone with enough motivation, aptitude and a photo of your face at lunch time could be knocking on your door later that evening. Not a problem if you don't have any enemies/crazies in your life right now, but that could ostensibly change the next time you piss off a crazy cager with a dash cam and a decent level of IT literacy.
With enough motivation it actually doesn't matter if you posted a photo or not. Someone could probably find you if you have any digital footprint at all.
Or so say my buddies who work in infosec at any rate...