Well the hardware is definitely there to support what you want. Gigabit ethernet, 70 GPIO using LVTTL for single ended operations, which can be configured to run in differential mode if you end up having signal integrity problems. The question is software. There are many ways you could do it. It doesn't sound too hard. You could run linux and write some user software and utilize sockets to get the data off the ethernet port. Then, you could feed a verilog module that actually drives the data out to the GPIO. Just some ideas.
The same can be done with an SD card but instead of interfacing with sockets, you would read from a block device, the SD card itself, and that would just be regular file I/O at that point. I've never done it but I think it goes something like that.