I think Apple was on to something important from a UI and usability perspective thirty years ago when they started building Hypercard. It is now coming to life again on mobile and I think this will be the most interesting battle ground on mobile in the years to come.
I don’t know about card interfaces being “the most interesting battleground on mobile”, but Wilson is indeed right about Hypercard being far too ahead of its time. History is littered with examples of great ideas which came too soon; consider, for example, the Newton and Microsoft’s early attempts at tablets. The former was fatally hampered by a lack of a ubiquitous connection to the internet, while the latter lacked — among other things — compact, powerful, and cool-running silicon. That’s not to imply that adding a cell network to a Newton would make an iPhone, but these products, like Hypercard, were the culmination of innovative ideas and brilliant engineering, but which lacked elements critical to overwhelming success.
Having said that, Hypercard enjoyed an illustrious history in niche and unexpected markets. It wasn’t a failure by any means, but nor was it a mainstream success. It never achieved the level of adoption it deserved, however.