Sounds somewhat similar to the IBM AS/400 (renamed many times). Applications were shipped as byte code and translated to the local machine architecture. The translated byte code was appended to the application, a but like NeXT fat binaries or OS-X's universal binaries.
The native byte code was 64bit, though iirc the first implementation used a 32bit address. The result was you could ship an application once and when it came time to move architectures all you had to do is one command to retranslate the byte code.
Very neat. I'm not sure why this approach hasn't been used more often.
EDIT: Looks like they're going exactly the AS/400 route.
The book "Inside the AS/400" has some really cool exposition on the unique aspects of the AS/400. If I remember right, the disks and memory are in a single address space, and of course, there is a relational database built in to the operating system.
I have seen the binary translation in action: it was required when POWER6 machines came out. On a POWER5 machine, I remember it taking around 20 minutes for an application that was around 20 MB zipped, but for software licensing reasons not all of the server models exposed the full performance of the processor, so that might not be representative. And at any rate, like the OP said, it's a one time thing, and then the translated version is kept.
There was the OpenGroup's Architecture Neutral Distribution Format, but I'm not sure if it was ever fully realized. Around the time that was proposed some real serious energy was put in to C compiler optimization, across the industry.
It does free them up in the future, they can make bigger hardware changes and just have to supply a bitstream player for the older code. I have a difficult time envisioning the architecture changes that make tons of sense to Apple right now though, other than like swapping video on their ARM chips and stuff like that. Running iOS apps on the desktop might make a ton of sense for some of them or some sort of tweener between the iPad and Mac book.
We were thinking on the same lines. IBM System/38 was truly a brilliant, integrated design in so many ways. Even had capability-security built into the hardware. Check it out at the reference below. Intel made a monster of a system too. Would love to have either on a SOC or an inexpensive server.
The native byte code was 64bit, though iirc the first implementation used a 32bit address. The result was you could ship an application once and when it came time to move architectures all you had to do is one command to retranslate the byte code.
Very neat. I'm not sure why this approach hasn't been used more often.
EDIT: Looks like they're going exactly the AS/400 route.