Rubbish, unless you are doing bare-metal programming on the PC (and no sane person would do that).
No, it will not work - USB 1.1 (as used by most FTDI chips) runs on a 1 ms cycle. Even with USB 2.0 (as used by some faster FTDI chips) runs on a 0.1 ms cycle. This means that any time you need to read a port then set some outputs based on the inputs, you have an absolute minimum of
0.2 ms latency - three orders of magnitude too high for an eprom emulator. For proper emulation of the signal sequencing, you would need several read-write cycles making it even worse.That's almost right - but drop the "PIC". They are horrible devices, and too slow here. Even using a decent small micro like an AVR, you couldn't emulate an eeprom at more than about 1-2 MHz. And if you have a chip that is fast enough, it is difficult to get consistent timings.
A much better idea is to use a small programmable logic device with a ram chip and a USB connection. You don't need much - a 128 macrocell PLD would be enough if you use an FTDI chip for the usb connection. Or you could buy one of FTDI's modules with a Cylone FPGA - it's overkill, but easily available and ready-made.