Stephen Hackett:

Google Now, Alexa and Cortana have all removed the boundaries between what information is local and what’s not. Apple’s not quite there with iOS 9, but I think iOS 10 could push it to the next level. Why maintain two services, with overlapping and somewhat confusing feature sets, when a single, unified experience could get the job done?

It would make perfect sense for Apple to merge Siri and Spotlight alongside the introduction of the rumored Siri SDK.