If I had the space or the money, I'd love to see M.A.S.K. figures and vehicles back in the mix. I never had any of the toys as a kid, but watched the show religiously. A modern, articulated line of these figures would be awesome, and I could even see them building a movie or show around it again.
I picked up the Sectaurs line from Zica and they are all kinds of awesome. I'd love to see small 3 & 3/4" articulated, well sculpted runs like that of several animated 80's cartoons. Silverhawks, G-Force, Super Friends, etc. I know we have had various offerings in the past, but I think a well done, Thundercats would be at the top of my list.
For 6" stuff, I'd be all in on an Indiana Jones figure, but probably not a whole line. I'd rather see 1-2 stars from all the big 80's movies in a Black-Series-Like similar format (I'm a big fan of scale and don't really like most McFarlane designs). I think a 6" Schwarzenegger across all his movies would be sweet too. How about a 6 figure lineup of Terminator, Dutch, Ben Richards (Running Man), Douglas Quad (Total Recall), Jack Slater (LAH), and Conan? And a BAF pack-in of John Kimble with his trench coat and shotgun!