Just my two cents...
If "technical dilution" is the question, I read in an article somewhere that the 2nd Doshu simplified the aikido curriculum and that weapons training is not as emphasized there. So in terms of quantity of techniques, there is some "dilution" compared to what O-Sensei originally taught.
I don't think however that this has necessarily decreased the value or utility of the art since I still read some posts by people saying that aikido saved their lives in a self-defense situation. I guess the value that some people attach to the original technical curriculum is the same as the value that we (or at least the historians) attach to historical items or places. They preserve it so that they get an idea and appreciation of what it was like then.
One could argue of course that back in the time aiki-jujutsu was first created, some of the techniques we know now were probably not even invented at that time. Or that the sankyo as O-Sensei learned it might not be the same sankyo as it was done hundreds of years ago when the technique was still young. So change or improvements on technique are inevitable.
So the concern would actually be, how much can the techniques be safely mutated without them eventually turning into a mere dance or coordinated stretching exercise. At least in feudal Japan, there was the battlefield to serve as a check and balance to weed out ineffective techniques or ineffective mutations of techniques.
As has been said already, no one can safely answer that question. But it's nice to ponder about it now and then.