In what way? All I've seen so far about "rootless" or what Apple is actually going to implement or what it will mean for users is just pure speculation from tech sites.
The only factual piece of information I know of that is likely related to "rootless" is from a WWDC 2013 session[1] about kexts, in which an Apple engineer said this:
> I'm Jerry Cottingham, I'm an engineer on the Core OS IO team
> ...
> And another warning I'll throw out here is in the future as we start to lock down the /System folder, you might actually get write errors. So when you try to install a kernel extension into the /System folder, the write itself may fail.
That seems to be about OS X. He also says, "So if you're trying to write a kext for iOS, we don't allow that." Did they ever allow third-party kexts on iOS? I'd be surprised, but maybe they approve it for some peripheral drivers or something.
That session happens to be about OS X kexts yes, but it's just where that piece of info happened to slip out. Clearly they've been planning to do at least that much for quite a while now. I wouldn't be at all surprised if they start using a completely separate system partition on OS X like they already do on iOS now.
As far as I know the release versions of the iOS kernel don't support kext loading at all. Most likely, MFI participants are encouraged/required to use standard interfaces or request inclusion of specific functionality if it isn't there already.
The only factual piece of information I know of that is likely related to "rootless" is from a WWDC 2013 session[1] about kexts, in which an Apple engineer said this:
> I'm Jerry Cottingham, I'm an engineer on the Core OS IO team
> ...
> And another warning I'll throw out here is in the future as we start to lock down the /System folder, you might actually get write errors. So when you try to install a kernel extension into the /System folder, the write itself may fail.
[1] http://asciiwwdc.com/2013/sessions/707