One way of looking at it is that the when the Mishnah was completed that was when basic Oral Torah and much of its principles had been completed. What came after was the style of Jewish study that the Torah called for in developing a Torah based culture. I.e. the reason that Hashem gave the nation of Israel the written Torah/oral Torah was/is for said Israeli nation to use it as to form the basis with which the Jewish nation's philosophy, politics, geopolitical, economics, science, mathematics, financial, inter-persoanal, admistrative, moral, miltary, etc. would be determine and developed as a society in any given generation past, present, and future.
It is similar to a statement made by Neil deGrasse Tyson about science.
“But you can’t be a scientist if you’re uncomfortable with ignorance, because scientists live at the boundary between what is known and unknown in the cosmos. This is very different from the way journalists portray us. So many articles begin, “Scientists now have to go back to the drawing board.” It’s as though we’re sitting in our offices, feet up on our desks—masters of the universe—and suddenly say, “Oops, somebody discovered something!”
No. We’re always at the drawing board. If you’re not at the drawing board, you’re not making discoveries."
Torah study in Torath Mosheh and Orthodox Jewish communities is similar.