I Hope this happens.
In my lab I have a 1,1 and a 5,1.
The 1,1 runs Dual 3.0 and the 5,1 has Dual Quad 2.26. The 1,1 is frequently "snappier" feeling and yet I look at it as neutered, or less potent.
I have spent some very long hours working out those nifty Fermi EFIs, but they fall on deaf ears in the 1,1. I just imagined how incredibly awesome it would be to run an update on it and have it suddenly be back on same playing field as the 5,1.
And I am 95% certain that the EFI64 for a 1,1 already exists. Look at the 3,1 and note how similar it is. My guess is that it was developed with 1,1 as starting point. SO sitting in the Apple labs somewhere in Cupertino, in the back of a testing lab, or in a storeroom, is a 1,1 running an EFI64. It is likely that it isn't perfect, but could be finished.
But do consider what would happen if such a thing got out in public. Anything that did NOT have an EFI64 would STOP working. SPecifically, Nvidia 7300 and 8800GT cards would not show boot screens on next boot and would need to be replaced. All ATI/AMD cards would be fine as they use a universal EBC style EFI. (exception being X1300 and non-updated X1900XT cards) I asked an Nvidia engineer that I converse with why they went with EFI32/64 instead of EBC as AMD did and got a silent response. I imagine there is a reason.
So any other peripherals that have an EFI32 on them would also quit working.
In other words, APple would open a potential FLOOD of support questions. Most people REFUSE to read much and just expect a custom-tailored support answer for their own personal consumption. No matter how many checkboxes they had "agreed" to or warnings posted, there would be literally thousands of "dead" computers. And instead of helping people post insanely cute puppy photos from their iPhone, the genius bars would be overwhelmed with people bringing dusty, long forgotten 1,1s in and demanding satisfaction.
They would literally have to train every genius at every service location all about this long forgotten machine. So add that cost to the equation. Waking that sleeping dog would be rather pricey.