* I took the liberty to correct your sentence, hope you don't mind ; )
The possibility that all wiiU versions (save for a devkit) will be able to run only software specifically signed/encrypted for the given unit off its SD/USB has two implications:
1. The consumer will never be able to update their console OS (i.e, flash their fw) unless the console was hooked to the net (where a server can sign the package with the unique key, etc), or they had the fw on an officially printed media. That can be a nuisance, but is the lesser problem by far. The bigger one is..
2. As a developer of DD content, you'll always need to burn your builds on a disk, just to be able to let your QA test what you've done. That can be a major hurdle for the development process. That is unless you had the vendor's console-specific sign keys to all your QA units. Which again turns the testing into a hurdle, albeit a smaller one ('Which idiot mixed the SDs for the QAs again?') Which takes us to the next point..
The units I liked to are development units, but not devkits. They are bog-standard units with normally two tweaks: they can read 'dev-cycle' media (i.e. non-officially printed media) and they may or may not have a bump in the memory (I don't think the wii one does). All that is done so that QAs can run early/debug builds off whatever the development-cycle temporary medium is - normally some sort of writable optical medium, but nothing precludes that that included some flash-based medium as well. The reason why they're not actual devkits is that a devkit is massively more expensive, and normally requires pairing to a PC to be able to function properly. A company may have a few devkits hooked to workstations, and dozens of stand-alone QA units that sit with the QA department and whose purpose is to run test builds - nothing more. Sometimes the press gets access to such units, which gives them the ability to run pre-release copies of games. Yes, during the start of a new gen normally devkits appear first, and then test/QA units appear later (as they're much closer to final retail hw). Whether nintendo have already prepared their wiiU QA units for release in the wild or not (possibly not), does not indicate what nintendo will bring to the show floor. Whatever it is, it will likely be functionally closer to a QA unit, and not to a retail unit (which, again, could be just a matter of firmware). So the entire argument of what a retail unit can and cannot do is nigh irrelevant to this discussion.
