Sheboygan was a favorite of ours, too. TSR was going to come out with a large boxed edition with plastic mini-monsters, etc., a bit like the current hit Mosterpocalypse, a real quality production. This was back in the nineties, I think, when TSR had taken over SPI and was doing big deluxe board games similar to the Milton Bradley line (Fortress America, Samurai, etc.). Unfortunately, no one in the company thought to contact the game's designer Greg Costikyan who at that point also owned all the rights to the game as his intellectual property (apparently rights reverted to him when SPI went bankrupt to TSR rather than going to the latter). He brought suit when he heard about it and TSR had to cancel production of the game as, I suppose, they refused to meet his terms. In fact, I think they were fairly far along in the production cycle. It was a fiasco as they'd been advertising the game, and a lot of us were really looking forward to it. But Greg was right to protect his interests.
I suppose FFG could reprint it, but they, too, would have to buy the rights from Greg. It might be simpler to design their own. Lately I've felt they've had better luck with in-house designs than those they've licensed from other companies.
I also enjoyed Amoeba Wars a lot back in the day.