Because Oculus is selling a product that is not a DIY kit, there are patent and licensing issues to deal with if they want a frequency-based magnetic tracking solution (as licensed to and used by the Hydra). They may have to work their way around the IP, or use the expired-patent DC magnetic tracking method.
There has been some information leakage about what they may be working on for absolute head tracking. There was this tweet:
... which may have something to do with this thread:OculusVR has snatched Nirav Patel from Apple & will use Adjacent Reality tech to track head position.
The Adjacent Reality open source wireless head/hand Tracker
http://www.mtbs3d.com/phpbb/viewtopic.php?f=138&t=15184
Knowing that Nirav Patel is nrp, we can put those two bits of information together and make some educated guesses...