Reading these comments, I'm reminded yet again of all the classic ThinkPad virtues we used to take for granted -- that keyboard; the trackpoint; the clip-on battery pack; the durability, practicality and maintainability.
So make it a late IBM-era or early Lenovo-era model with at least 32GB RAM, i7 processor, SATA-3, two SFF bays for SSDs, 1Gbps Ethernet, and plenty of USB3 ports. Aspect ratio 16:10 or 4:3. Windows 7 Pro 64. I don't care how thick it is or how much it weighs.
I do hope Lenovo goes ahead with this idea.