Today, Siri is known to most of the Android world for being inferior to Google Now. But back when it was first announced, it was a big frickin' deal and the crowning feature of the iPhone 4S. You may be surprised to learn, however, that Siri was almost an Android exclusive.
Way back in the pleistocene era – AKA 2009 — Verizon was in talks (get it?) with Siri's parent company, Nuance Communications, to be an exclusive Android partner. The company had even gone so far as to film commercials featuring Siri. Then Steve Jobs swooped in and the whole deal fell apart.
In just a single meeting, Jobs convinced the company to accept their buyout offer and the rest is history. After buying Siri, Apple used it as a bludgeon to attack Android and prevent them from developing a competing voice recognition system. Funny, since it almost WAS an Android feature.
There's a pretty long article detailing the history of Siri in the Huffington Post, and I would be interested, but we all know that Google Now eats Siri for breakfast. Who came up with what first is by now irrelevant; Google's services simply get more done, faster. As to what will become of Siri, I think Apple now needs to roll out some serious additions that can predict what people will ask before they do so. Otherwise, I can't really see this feature going anywhere.