Bidirectional Quine Chain
3 external displays DOES work.
I am on a Late 2013 MacBook Pro. I have 1 monitor on the HDMI port, 1 on a displayport to HDMI adapter, and one on an ACTIVE displayport to DVI adapter. I'm thinking that the trick here is to use an Active DVI adapter (mine is from Accell)
I have a Macbook Pro 15" Retina (mid 2013). I run three monitors with it. From the mini HDMI port, I run an old Apple Cinema Display. From one of the Thunderbolt ports, I run a 2013 Apple Thunderbolt display. From its Thunderbolt port, I daisy-chain another 2013 Thunderbolt display.
I have experienced no difficulties with running all three displays at once (typically watch Slingbox or Netflix on one, working on Photoshop with another, and running other apps on both the MacBooks' native display and the old Cinema display monitor.