Where is there a discussion about which laws/traditions/decisions will become invalid when the Messiah comes?
Why do the sages think that certain laws/or "mitzvoth" (if that helps in the search), or traditions /decisions will become invalid כאשר יבוא המשיח?
A similar (but different point) is made in this exchange, inclusive of information, as to which sages think likewise: When the Messiah comes, will the decisions/laws of Chazal still be in effect?