The Ohr Hachaim (Bamidbar 3,45) says a chiddush that seems to not have any obvious source, that לעתיד לבא (after the arrival of mashiach) the Avoda in the Beis Hamikdash will return to the firstborn! (we know that they did have this role till the חטא העגל).
I have seen many good questions on this chiddush, but the following one stood out. The Gemara Tannis 17a states (according to the חכמים) that a Kohen בזמן הזה (nowadays) may not drink wine because perhaps the Beis Hamikdash will be rebuilt then and he will be called to return to service in the Beis Hamikdash, and one cannot perform the Avodah in an inebriated state.
The question is if the Avoda will be done by the firstborn (בכורים) also, then why don't they have the same prohibition like the Kohanim not dring intoxicated beverages?
Perhaps one can say that only the firstborn of that generation (of moshiach) will merit to do the Avoda, but the Bechorim of today lost their Kedusha by their "Pidyon" Haben... What are your thoughts?