More a comment about Mike's new essay, then a reply to the post.
The Mantra in the Digital Age is "Faster, Better, Cheaper!"
Thiry years ago 8 bit processors were the norm, running at kilohertz speeds, costing hundreds of thousands of dollars. Look at what you can buy for your home today: 64 bit processors, running at 3 Megahertz, costing about $1500 - $2000.
Conclusion: 4/3 is dead, long live full frame - Michael's essay is a harbinger of the future.