They're the signals for a TFT panel; however, there are only 8 of them (the other 8 are GPIOs 2-9, which are very much in use). If you disabled the display, you could in theory drive an 8-bit active display - or even a TV out, using something like the Chrontel CH7003. ISTR there's LCD0-7, PCLK, LCLK and FCLK.

Another thing you could do is use bits 1-3 of the video data (the VFD only uses one in every 4 pixels from the video controller) and easily hook up another 3 displays that could show different things

Hugo