Everything the author says is true
But we are many many years away from Siri/Google Now/Cortana starting to replace apps that do more than allow setting alarms or looking up individual pieces of information. For complex tasks like booking flights, unless you only care about schedule (i.e. you aren't paying for it yourself) choosing flights is an exercise in trading preferences. Then you get into the questions about what is the best time to book, since prices aren't stable and unless you need to travel ASAP you might get the best price six months in advance, six weeks in advance, or six days in advance!
When I do book, do I want to save money by waking up at 4am, or by having a 5 hour layover between flights? This flight is cheaper and has the best schedule, but the only seats left are middle seats. This flight looks good, but its the last flight through O'Hare in the evening during the summer (for those who don't know, this is a terrible idea as a raindrop within 50 miles of O'Hare seems to slow everything down and the last flights out to a particular destination are often cancelled, especially if they're to smaller airports)
I'm not sure I'll live to see a virtual assistant be able to do a proper job of that, because I'm fighting against the airlines' computers, which are updating prices hourly and trying to optimize against consumers and make sure the more convenience I want the more I have to pay.