Edit: And the spec has since gotten multi-vendor interest. From Microsoft:
> We're excited about the potential for this feature set to resolve some of the performance and privacy problems of alternative approaches, and we have been talking to publishers who are interested in utilizing these technologies to provide accelerated experiences.
For now, his tweet is all the signal we have from Apple.
Microsoft has ripped a fair amount of stuff out of Chromium already.
15 month :)