I'm not sure if this was on a published roadmap or they just snuck it out there, but this feels like a big deal to me. It opens the door for third party manufacturers to make cheaper alternatives to the iWatch and to explore styles that Apple won't risk.
The Huawei announcement I posted a couple of days ago makes more sense now, and I'd expect a lot more manufacturers to start trying to push into the iOS market soon. The fact that the watches are platform agnostic may also make them more attractive to consumers, removing as it does the need to tie yourself to a particular OS.