CyanogenMod developers passing on Samsung Galaxy S4
Nobody at Team Hacksung (the team behind Galaxy S2, Note, S3, Note2, G Tabs... official CM ports) plans to buy it, neither develop for it. There are two variants which will be a pain to maintain, [and] the bugs we have on the S3 will probably be there on S4, too (camera), and we all know Samsung ability to release sources while staying in line with mainline. Yes Qualcomm releases sources, but Exynos sources we had were far from [working on] actual Galaxy products. I'm pretty sure the same will happen for this one.
That's a uniform "no" from us.
The other developers are saying basically the same. Codeworkx, Entropy512, and kernel developer Gokhan Moral have said they refuse to develop for the Galaxy S4.