Many S5 features depend on its framework, which is surprisingly hard to port. If you want to rush it, maybe we can have a look-alike ROM with 70% similarity in looks but 10% similarity in function - not what you wanted, yes?
Besides, you outta buy a S3 or S4 because they have a much better chance of having S5's ROM ported. Galaxy Nexus is born for AOSP
Sent from Google Nexus 4 @ CM11