Oh, sure, they'll shuffle along for some time. They'll sell some stuff. They'll make some money. They'll command some headlines. They may even do some new things. But as tech giants, they're dead.

This was driven home in wonderfully complete fashion this past Wednesday, thanks to a trio of events. If you don't follow the seemingly uninteresting, enormously lucrative, and, in fact, endlessly fascinating world of enterprise computing—computing that helps run big businesses—you may have missed them all. But they were big news in the enterprise world. And together, they show just how dead those giants really are.

First, Pure Storage, a Silicon Valley startup that sells a new kind of hardware for storing large amounts of digital data, made its Wall Street debut.