Gamecube games to be downloadable on WiiU?

Mixing actual hardware with emulation isn't as easy as it sounds. I guess you'd probably need to insert microcontrollers between the memory card bus and a section of the Wii-U's flash memory, which likely defeats the point of cost-cutting.

They'd probably be cheaper to include the physical ports.

If you're going to do emulation, it's most flexible to do the entire thing in software.