It's probably even legal to make a batch script to rip the models off a game disc that you own. Probably even legal to distribute said script as long as the script itself contains non copyrighted material. You could go so far as to make a script that would copy the model, convert it, change the animation data, and whatever else was needed. As long as you do not distribute any copyrighted material yourself it's ok. Modders do it all the time. Take futurewars for instance, a mod for Armada 2 that completely circumvents the install of Armada 2 itself. It asks for the game cd, rips what it needs off the cd and installs the game on it's own. You wouldn't even need to modify the ff7 game files if you had Aali's renderer installed as it can load loose files outside of the lgp. Is all this really necessary though? Everyone knows there is going to be either a remake or a hd update eventually. With the disaster that is FF14 they're eventually going to need the money unless 13-2 fixes all the problems with 13. They've already said they're going to release an hd update to 10 for the ps3 and vita. Since technically 10, 10-2, and 7 are LOOSELY considered a trilogy hopefully if sales go well they'll do the same to the other two. With crisis core, dirge of cerberus, and advent children they've been fleshing out the timeline. They've said before that a REMAKE would take more time than is feasible to do. I've never heard anything about a hd update though. Which, with all the scrutiny that players seem to have for FF7 itself it's probably the best way to go. Keep the battle system and character system along with the plot the same, just add voice acting and update the graphics.
Although personally I would like to see a full remake with a fuller plot or maybe a side-plot, a limited branching storyline that comes back together for the same ending, sphere grid or crystarium like character progression, a battle system reminiscent of Crisis core or XIII-2. That's what I'm hoping for