prophecy has never ended. it is written it was given to fools, but it was never taken from the prophets. according to Jewish scholars, there were 1.2 million prophets in the biblical time. which brings me to an insight I had.
we all agree that then the halacha was the law and God's will.
we know that prophets had so much power that they could face kings, they had the public's ear and I don't recall anything else but understandably they had very significant and representative roles in the nation life.
we know they were very educated and very rightous. which make me conlude that the prophets were Rabbis. In Judaism, we know that Elijah was definatly a rabbi
Yoma 9b reads כִּדְתַנְיָא: מִשֶּׁמֵּתוּ נְבִיאִים הָאַחֲרוֹנִים חַגַּי זְכַרְיָה וּמַלְאָכִי נִסְתַּלְּקָה רוּחַ הַקֹּדֶשׁ מִיִּשְׂרָאֵל, וַעֲדַיִין הָיוּ מִשְׁתַּמְּשִׁין בְּבַת קוֹל.
formal propehcy ceased
Bava Basra 12a discusses the cessation of all forms of prophecy by the destruction of the temple, but that would just be the cessation after the period of substantial decline (in that, if you check the Ramban there, what is called "prophecy" is more like an inspired understanding of the right answer to a halachic issue -- אעפ"י שנטלה נבואת הנביאים שהוא המראה והחזון נבואת החכמים שהיא בדרך החכמה לא נטלה אלא יודעים האמת ברוח הקדש)
On 12b R' Yochanan's statement about imbeciles and children is shown but he is referring to after the destruction of the FIRST temple (see the Chiddushei Aggadot -- מיום שחרב בהמ"ק ראשון קאמר דבבית שני לא היו נביאים אלא בתחלת בנינו היו חגי זכריה ומלאכי) and the "prophecy" that children and imbeciles have is sourced quite differently ("אבל נבואת השוטים ותינוקות אינו אלא ע"י שד"). The two examples of "prophecy" on B"B 12b show the totally different nature of "prophecy" -- more like "wild prediction."
As to the question of what constitutes a "rabbi" there is much discussion. Classical smicha? Just being a teacher (rav umanhig)? Something else?