Good post Ken.
I also saw old video of O sensei and it is true that his ukes are attacking from very far. May be for demo purpose only, who knows.
You can't go back forever. And you can't limit your techniques only to kicking - we are not doing kickboxing LOL
Yes, such attack I'm interested to talk about unbalancing. Most experiences attackers do it that way. How will you structure a training to get your students familiar and what kind of training solution you can see?
My comments were in response to your concerns as posted. My general point is that attacks come fast and hard. Otherwise run away. If you can't run away for some reason and the attacker wades in on you, kick him or strike him. If you don't know how to do that then Aikido (meaning unbalancing him with his own attack energy) is still quite possible... but will require a higher level of skill/experience. Not something you'll get overnight. Aikido is not an easy art to learn to do at the higher levels.
There is a difference between how to train beginners, how to train senior students, and how to respond in a self defense situation on the street. They are related by not always in an obvious or straightforward manner.
Beginning students should, in my view which I inherit from O Sensei via Saotome Sensei, should practice in a highly cooperative manner. This can be too cooperative. It's a thin line. But basically in a highly cooperative manner. By training this idealized way Uke helps Nage to learn to draw out of a real attacker the desired responses. It cannot be taught directly. The unity of opposites of Uke and Nage when training in a cooperative manner teaches both partners things that can't be directly taught and are hard even to put into words. This is what Saotome Sensei calls the seventh sense. Cooperative waza does not preclude the use of exercises that may be static, Etc. Beginning students need to trust the system that O Sensei developed.
Advanced students should engage in a variety of training approaches to develop different skills. They can give each other feedback about when there are weaknesses in the movement/technique. This should not take the form of resistance that leaves Uke vulnerable. Eventually students must understand weapons defense, take musu aiki, Oyo henka, reversals, and randori. All Aikido training should be leading students to handle multiple armed and unarmed attackers. Otherwise it is of very limited self defense value.
A new student in a dojo may give their balance too freely and not recover it. Or the new student may fail to follow all together. These are not the behaviors of dangerous attackers in self defense situations. If we want our bodies to respond correctly when attacked by experienced attackers, we must train with the assumption that the attacker will not make such mistakes as these which leave him completely vulnerable to counter attacks. When a real attacker fails to recover his balance, run away. When he fails to follow, stands there like a statue after attacking, either strike, throw (harder to do without energy from the attacker), or run away. If the attacker keeps or regains his balance then initiates a new attack blend and unbalance with this new attack energy, strike, or run away. There are higher levels of Aikido, which one strives towards, and then there is survival. Much of Aikido is about, as Saotome Sensei says, risk management. Or as the character Mr. Miyagi said, "best defense no be there." Aikido, generally speaking, replacing the counter strike by guiding the attacker off balance, but a failure to understand the option to strike leaves you vulnerable. At the very least it forces you to perform high level Aikido. In case of mistakes it's good to have plan b, c, and d.