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.
Given that you're talking to the author of Hidden in Plain Sight
, and that much of that book discusses in great depth exactly this question, you might want to read the book and address its specific arguments rather than offer a blanket, unsupported opinion on the matter. The conversation's gone a bit beyond "Well, I