in my eyes 10 demigods are enough for now so i wouldnt buy more, but i would certainly pay for a map pack with some 3vs3 maps. if there was an expansion in the future with a pair of new dgs, few more maps, some items, perhaps a really slight ai upgrade i would get it as well.
I am absolutely against map packs. The reason why these "map packs" have become so popular over the years is because of consoles, a medium that lacks the dedicated mod community that we have. I will never, ever, pay for a "map pack" on the PC. It is absolutely bull crap. All CS maps were originally designed by fans and the mod makers and all competitive SC maps usually are fan made.
New Demigods would be another subject. I might pay for new Demigods if there were more people playing and a brighter future for the community, but I'm not so sure at this stage.