Okay, so I'm guessing we'll never see a Classics Modulok, but here's how he could be done as easily for Mattel as possible, in my mind.
Release Modulok as a fairly basic figure, using the basic buck but with all the joints using whatever pop-off mechanism they're using for Trapjaw. Include the second head, split-peg neck, and a belt and chest plate with pegs to accept other limbs.
Then, release a limb with every other figure that year. So Modulok is a basic stand-alone figure, using the basic buck with skeletor feet and arms, making him easy to do. Plus, tossing one limb in per figure for the year gives you 11 other bits.
Just an idea. Modulok is another figure MIA from 200x, and my second dream character after Extendar (MAKE EXTENDAR!!)
I'd love to see other ideas.