Five Nights at Freddy's - "FNAF 5 CONFIRMED! PLZ SCOTT! FNAF 4 IS IN 1983! FREDBEAR DIDN'T CAUSED THE BITE OF 87! FOXY/MANGLE STILL DID!" MFW...

The '83' thing could refer to when FredBear's Diner was first established. Like most (if not all) restaurants have the year when they first opened. I'm surprised that not to many people think about this. Please refer to this video:

Even if the 83 thing is true, which it might be given Scott's style, there is no 5th game. It's. Over.