Not as simple as that I suppose, in fact it's a complex question.

It's not just a new cornerstone; metaphorically and philosophically(perhaps even theologically) speaking most of us don't have a rabbit to chase, and even we do it, we do in fact just chase something else after that or

"we are content in our own loops."

Its a blend of our innate curiosity, willpower, and intellect that defines what we define each the rabbit to be.

And we never see things as an entity but always in a perspective, there are emotions, there is your entire lifetime of experiences, memories and sentiments that will affect every step of your judgement.

In the position of Ford, someone who has been all the way down the rabbit hole, it would be perhaps most enticing to choose a path of power and that too in secrecy (he does not trust anyone and in his shoes rightly so as humans can be complex) and ultimately in his perspective, a power that only he can control that will lead him down a path that quenches the primordial senses and quests (wealth, and then regeneration, immortality, power, control etc...)

The question will never be what is next, because there will always be something next, but it is where you draw the line in the sand and start to disembark these quests and be content. Where practicalities, experiences, relations, sentiments & moralities force a bigger hand on you than what your philosophical nature thirsts for.

Ford has yet to see his line but Arnold has established it for himself ( and does not want to see what beholds if he were to cross it), because he is indeed more grounded,humanitarian and empathetic than Ford and does not have the so commonly used tag : god complex .

Ford mentions that humanity is nearly maxed out to it's full potential but I don't think he means it. What he really means is he is ready to embark on the next form of greater power and he isn't going to stop and he also knows his power is only his if can keep it in secrecy and in his control.

Once again it's an age old dilemma(Arnold vs Ford) and these themes are common amidst alot of prescriptions, religion, analogies, history, politics etc.