Software Design is not mathematics - for lots of questions in this area, there is not objective "right" or "wrong", only opinions about "better" or "worse" based on certain experience. So I would not expect any change for questions which are opinionated to a certain degree. On the other hand, purely opinionated questions were closed very quickly by the community in the past, and I expect this to happen the same way in the future, with or without the name change. Note the goal of the site's rebranding is not to change the current scope, only to make it more transparent.
However, the two linked examples your question mentions will probably not be closed as too opinionated. That is because they do IMHO- as far as I can see - not encourage opionated answers, quite the opposite:
the first one makes the wrong assumption that the use of "const" in C++ is only a matter of readability. It is objectively true that this assumption is wrong (see second answer). And it is objectively true that readability increases by the tabular parameter formatting presented in the topmost answer
the second question asks if the usage of TDD makes Defensive Programming redundant. The answers explain well that this is objectively not the case, because they address different types of failures
So what I see in your question above are at least 3 wrong assumptions:
"purely opinionated questions seem to be welcome here" (they are not, and I saw a lot of people complaining about the opposite in the past - that their opinionated question was closed overhastily)
"when a question is about readability, it will cause opinionated answers" (readability can surely be based on personal opinion, but a question like "is XYZ just a matter of readability, or is there more behind it" can typically be answered by facts)
"TDD and Defensive Programming are just buzzwords, and a comparison of them will be purely subjective" (see above why this is wrong)
Though all of these assumptions are plain wrong, I gave your question an upvote, either, since it is at least a good occasion to explain the difference between "good" and "bad" subjective questions.