The promise of rulership for the 12 was already given in Mathew 19:28. it was repeated after the last supper celebration, was again not part of it.
The slight of hand that wt speakers perform at the memorial talk, to slip in the kingdom covenant instead of the new covenant, is set in all the deceitful outlines.
In Israel of old, the Law covenant was for all, even the foreign resident. additional exclusive covenants were made for kings and priests.
Jesus passed the emblems to disciples with a distinct earthly hope. not anointed at the time.
If partaking of the new Covenant's symbols is indeed a prerequisite for salvation, as per John 6, wt is the deadliest organisation that could have been set up. Guaranteeing to kill 100 % of its members, because even the partakers die to go to heaven.