Yes.
You can upgrade the graphics card in the Mac Mini by
using an external graphics card connected via ThunderBolt.
Apple may not wish to support such things themselves, but third
parties might make them work.
The graphics "card" would become a graphics module.
There would be no PCIe connector, since the bus connections would
all be between a couple of chips on the circuit board.
All you'd see is a ThunderBolt cable leading to what looks like a heat sink.
No power cable. Just great graphics.
They could optionally add an HDMI or DisplayPort connector if
you wanted it to drive an extra monitor.
swSteve
Redwood City, CA