There seems to be proof to the above from a halachah the Shulchan Aruch brings in Hilchos Nesiyas Kapayim. The Shulchan Aruch (Orach Chaim 128:38) rules: “If a Kohen drinks a revi’is of wine in one go, he shouldn’t duchen. If he drank it in two goes, or he added some water, then he is allowed”. The Nosay Keilim [commentaries] don’t seem bothered with the fact that nowadays it’s forbidden for Kohanim to drink wine due to מהרה יבנה בהמ״ ק – “the speedy rebuilding of the Beis HaMikdosh”, therefore, it would seem that halachah lemaseh, nowadays Kohanim are allowed to drink wine.
However, we could easily refute the above proof, as it could be that lechatchilah [ideally] Kohanim should refrain from drinking wine, and the Mechaber is discussing what happens if bedieved a Kohen did. However, the widely accepted minhag nowadays, certainly seems to be that Kohanim are lenient and drink wine.
