"I think it is likely that Xcode 6.3 will be launched around the time OS X 10.10.3 ships. That could be around the time of the Apple Watch launch or not. There's nothing really specific to the Apple Watch in it but there are no API for the force touch trackpad that should probably be released before or around the same time as the new Macbook so I would think that is the likely target." - Brandon Titus