The Gemara in Ta’anis concludes: אמר אביי כמאן שתו האידנא כהני חמרא כרבי – “Abaye said: In accordance with whose opinion do Kohanim drink wine nowadays? Like Rebbi”. Rabbeinu Chananel explains: The halachah follows the Rabbonon, and this is how Abaye conducted himself. Abaye was from Bnei Eli who were Kohanim, and he never drank wine, however, he was coming to answer what is behind the minhag of the Kohanim that do in fact drink wine, and he says, they follow the opinion of Rebbi. However, halachah lemaseh, the halachah is like the Rabbonon, and Kohanim should refrain from drinking wine nowadays.
[The Tchebiner Rov (Shu”t Dovev Meishorim 1:92, s.k. 2) asks, that we find in Berachos (42b) that Abaye would make a berachah on every single cup of wine that he drank on Yom Tov. It’s possible for the Beis HaMikdosh to be rebuilt on Yom Tov, as is clear from Rosh Hashanah 30a and Succah 41a, so it would seem that Abaye did in fact drink wine?
The Tchebiner Rov offers three answers: 1) He drank a revi’is of wine diluted with water, which according to the Rambam (Hilchos Bias Mikdosh 1:7) is ok for a Kohen to drink; 2) he drank with an interruption of longer than kdei achilas pras; 3) The Yerushalmi (Pesochim 10:6) says that wine drunk during a meal doesn’t cause drunkenness.]
