How long until some enterprising factory worker ganks a WiiU and sells it to a tech site for disection? Until then its all silliness.
That will only tell us some of the story. About the only thing it will completely lock down is the RAM amount, since the size and number of RAM chips can simply be physically counted.
Some idea of the CPU and GPU can be gained by looking at them (size, manufacturer etc), but only programmers and others in the know will really know what they are internally.
So to answer, yes the physical console will provide some hard info, but not the complete picture. Usually the complete picture is leaked by developers working on it. Which then has to be generally accepted as truth (think Wii specs, which AFAIK are still nothing more than widely acknowledged rumor, or 3DS)
Another good corollary is Apple, who like Nintendo refuses to reveal exact specs as a matter of policy, yet we tend to know what is in the iPad anyway (though, benchmarks help with that, which obviously wont work on Wii U)
I tend to doubt even Microsoft and Sony will release specs next time. When Sony downgraded the RSX and memory clocks late in PS3 development, they simply removed all clockspeed references from official specs, while they had been open with PS3 specs prior. Microsoft was open with 360 specs, but who knows if that will continue.
I would suspect it's better for MS and Sony to operate in a veil of spec secrecy than not for multiple reasons, one of which would be hiding them from the competition. Another would be consumers drawing wrong conclusions (EG, when slower clocked CPU's are faster than faster clocked ones, so the clock speed is misleading)
I'm curious about this as well. When and how did we finally get the specs for Wii?
I recall IGN coming with them. To a huge firestorm of criticism from people who refused to believe...