Teslas Master plan (https://www.tesla.com/blog/master-plan-part-3) expressly states an effectively zero marginal cost of energy as one of their goals. Tesla has not done so well on timeline predictions at times, but thus far, they have an unparalleled record at eventually accomplishing what they set out to do.

Has there been or is there any ongoing discussion of how the Bitcoin Network could and would be secured in a world of abundant electricity?

There are so many variables, that any prediction would of course be just a prediction, but has tehre been work done with this potential scenario in mind?