Most of the mobile devices are, in fact, powerful enough to develop for themselves, what they lack is mostly decent input ergonomics and redesigned UIs for the tools. (And in Apple's and a few other companies' cases, they have an excess of lockdown.), but that's not really the point.

I'll be using my laptops for the foreseeable future (seriously, people still use desktops?), but the IBM guy's point is that the mass market is moving on from what we consider "PCs". Geeks will absolutely still have them, other people not so much.