I'm not familiar enough with the details to be comfortable giving any specific timeframe, other than it should be coming sooner rather than later. It still needs a lot of testing, whatever fixes are required based on the testing, and (for most uses) a sync-up with a release for the phone.
We are doing some things to improve syncing performance, but there are some bottlenecks (basic app launch time being one of them - I think the fastest any app on my phone launches is about 2.5 - 3 seconds) and a lot of the slowdowns have to do with clients that aren't syncing often, or changes coming from multiple clients, etc. - things that require more work to handle rather than actually spending time passing data around. Those things aren't going to be sped much by local wifi syncing. (But as I said, we're working on improving those issues, which will hopefully make things better for everyone.)