It has been noted in other questions and answers on this site that Tolkien's conception of Middle-Earth has an imaginative relation to Earth history. Some salient sections of Tolkien quotes from answers to this question are worth repeating here for background:
Then a final one from an answer on this question:
"May I say that all this is ‘mythical’, and not any kind of new religion or vision. As far as I know it is merely an imaginative invention, to express, in the only way I can, some of my (dim) apprehensions of the world."
So the question is does Tolkien ever express in his own words that he himself is still living in "Middle-earth"—in an imaginative sense, I would suspect, but one in which Tolkien's time (A.D. 1892-1973) and place (Britain/Europe) he refers to as Middle-earth, rather than Earth or Europe, etc.?
Another way to state this is if Tolkien conceives the identity of what he calls "Middle-earth" as passed away, and what remains during his time is no longer Middle-earth, but simply Earth—or does he view "Middle-earth" as still continuing in his day.
Some might ask why this matters. It matters in determining the "voice" Tolkien might use in his narration of events, specifically in a fundamental difference between what is plausible for how Tolkien would voice a narrative aside in his writing, which is the basis for this question (and a difference in view on his voice as this answer to that question gives). So an answer here could resolve the validity of that answer to my question.
Clarifying How this is a Distinct Question
This question has been closed as a duplicate to one that it had linked to as background. But that other question is a very distinct question from this one.
That question is asking about whether Tolkien conceived of Middle-earth being a part of "our Universe." It was a question about where Tolkien imagined the stories of Middle-earth taking place. Fundamentally, it was a question about how he conceived his world of Middle-earth.
This question is asking how Tolkien conceived of himself in relation to his world. That is, did he perceive Middle-earth to be continuing as Middle-earth during his own time period, such that he was himself still living in Middle-earth.