Do all these new sensors and proprietary software (camera features, gesture features, etc) make it more difficult to develop customs ROMs for the gs4? Or will we just get ROMs that don't use all these new features and sensors
I think GS4 & Note3 development will be pretty similar to GS2, Note, GS3 and Note2.
AFAIK, for example, the AOSP based ROMs don't really support the S-Pen on the Notes, but that's more app specific.
Cameras have long been, and will likely continue to be a problem. Video capture rates may be lower, features like both cameras, sound in pictures, smart scroll may not be supportable.
As always, for stock features, there will be stock based ROMs. Take your choice, features or AOSP based.
As with all the other Galaxy S class devices, there will be two main variants: International Exynos Octa & US/LTE/Qualcomm. ROMs, XDA forum sections and many issues will be different for each.
I predict that many ROM devs will continue to complain about the lack of Exynos info and source code. But they will develop, as best they can. I'd like to see Samsung open up more, Sony and Qualcomm are better at open-ness.
And there will be at least one other group for the Qualcomm variants; I'd hope the US carrier variants will all be able to run the same ROMs, but previous experience is different I guess.
For the longest time and to this day you could not get the FM radio to work on CM without buying a $10 Spirit radio app.
1st post of my thread has links to free versions, as well as free alphas of Spirit2, with digital audio features for Galaxy S class devices.
I hope the proposed Android FM API will see success and provide more options.