The end of the final chapter (Circle, Square, Triangle: How to Be O-Sensei in Sixteen Easy Steps) asks some question quite similar to this post
by Ellis in the "Guests in the House" thread:
I agree with Mike and Mark that, truly, Ueshiba's aikido, at least, was always imbued with internal strength - and my opinion is that everyone else's should have been. That said, there are both other aspects of aikido and "other aikido's" that have developed. Just as aikido is not DR, many aikidos are not Ueshiba's, and many DR are not Takeda's. (There's a whole other story of concealment and HIPS there).
How I interpret that is that if one wants to do aikido without internal strength, there are plenty of aikido teachers to go to. If you want aikido with Ueshiba's kind of internal strength, it will be virtually impossible to find someone who can teach you the exact internal skills that he had. (Sure, Tohei, Shioda, etc. did aikido with internal skills, but they were different from Ueshiba's.) So you'll need to look outside of aikido for these skills. And if you really want to, you can then go and reverse engineer aikido. However, none of this is Ueshiba's aikido.
So basically what I read in the end of HIPS is: if you're interested in internal strength, why bother with aikido? Why not do what Ueshiba did, find someone who can teach you these skills and take it from there?
If you were drawn to aikido because of Ueshiba's incredible skills, it just might make more sense not
to study aikido...