Rene Ritchie, expanding upon the aforelinked tweet:

There’d been some speculation on Twitter and rumor reports about Apple possibly introducing a display with an integrated eGPU. Theory being, it would take some of the graphical processing overhead off MacBooks and/or facilitate a single-cable connection that could drive 5K. It sounds cool, but I asked around, and it’s not happening at the keynote or any time in the immediate future.

It looks like WWDC is going to be more of a software-focused event. And that sounds great to me.