Amdur san, my own view on the matter of aikido and "internal power" was summed up by you some time ago when you wrote: "there are hard internal arts, and soft external arts". Hence internal and soft are often, erroniously, conflated. In my experience, the matter is further complicated by the fact that the word "internal" is often used equivocally even by those with some experience in it.
Just as the internal is rather degraded by injudicious applications of muscle, so too is the external degraded by trying to make it something it is not. My own opinon is that aikido is not, (and here I admit the epistemological problem since I have not always been around) and never was an internal martial art. Or, perhaps better put, no aikido I have ever experienced has ever had elements of the internal in it. I have observed some very soft and exquisite aikido, but in my opinion the internal can be quantified, taught, and felt, and again, no aikido I have ever felt exemplifies it.
Now that is not to say that some teachers, with input from other arts, are not importing it into their own practice. Some most assuredly are making this attempt.But I think aikido is best served, and at its best, when it is treated like what it is, a rather sophisticated and effortless method of bone locking and throwing. In my opinion, this excellence is not achieved by "internal methods" but rather by very excellent external ones. Many martial artists seem to have made the implicit value judgement (without understanding the terms) that somehow the internal is "better" than the external, and I know of no tradition which maintains this. It is, I think, more to the point to think of them as different technologies.
One large difference (and there are several) between the two technologies is that the internal is initially learned by learning body shapes. When I once asked you about internal elements in your own weapons practice you replied something to the effect that: "I don't know if the internal is part of it, or it is just a perfect RECEPTACLE for it, but the TBR seems to be an excellent vehicle for the internal." I would make the same claim for the TSKSR (at least for the Sugawara ha) The shapes in older weapons work seem to suggest to the body the type of organization which can produce one of the sine qua non of the internal - the distribution of labor between that which connects and that which does the work. Or, as my own teacher says constantly, "Don't fight where there's trouble." It is a distinction between disparate elements within the system. A lack of "double weightedness" is another term for it. This does not even remotely imply to simply "go with the flow". It is much more complex. In any case, it seems to be the older styles of weapons work that have this type of body organization implicitly, whereas the big Chinese three have it rather explicitly. These shapes are most definately NOT in post-war aikido and hence virtually all aikidoka are, regardless of how softly they do it, "fighting where the trouble is". (Of course, as you point out, much, if not most, of what now passes for "internal martial art training" may in fact be a horse of a different color. There needs to be a good teacher, a good system, and a good student for all of this to gel.)
IF Ueshiba had internal power, and I have no idea if he did or not, I would posit that he got it via his weapons work, and I would also posit that the reason none of his students (that I have worked with) have it is that their weapons work is derivative and rather shapeless. This is NOT to say that their technique is not exquisite, just that it is a different technology.
So as to the question as to whether or not the internal can be brought back into aikido, I would suggest it never really was there in the first place. To try to bring it back will degrade aikido from a very excellent soft external art, into the sort of hodgepodge of parlor tricks that much of what goes under the banner of "aiki weapons" has become.