When people talk about productivity - about PowerPoint and Excel and how Google Docs and the cloud will or won't kill them, or messaging and the cloud, or how you need a PC for 'real work' - I'm reminded of CC Baxter and his Friden calculating machine. What killed those machines was not better, cheaper competitors but a completely different way to address the same underlying business need. Instead of hundreds of people recalculating insurance rates, the company bought a mainframe. The business need was being met, but the mechanism changed completely and the old tools disappeared.
This is how tech revolutions happen. There's no doubt that iOS and Android have completely changed how we communicate (WhatsApp, Twitter, Snapchat) and they're starting to really change the way we work (Slack, Google Docs, etc). Most companies are too big and too entrenched to change fast, but younger, smaller companies have moved to these new mobile first platforms. You're going to be hard pressed to find a startup these days who runs their business on Office and Exchange.
Things are changing as we speak, and in 10 years we may be surprised how little our day-to-day lives include a "real computer."