I've got a better idea. Let's see how Matthew uses the word ἕως.
Matt. 2:9 says "After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was." Are we to assume that this star is still fixed in the sky at that very spot to this day?
Matt. 2:14-15 says "So he got up, took the child and his mother during the night and left for Egypt, where he stayed until the death of Herod." Are we to assume that Joseph stayed in Egypt the rest of his life?
Matt. 5:18 says "For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished." Are we to assume that even after heaven and earth disappear and everything is accomplished, the Law will still be in play?
Matt. 5:26 says "Truly I tell you, you will not get out until you have paid the last penny." Are we to assume that even after the last penny is paid, you won't get out of prison?
Matt. 10:11 says "Whatever town or village you enter, search there for some worthy person and stay at their house until you leave." Are we to assume that the stay should continue after the leaving?
Matt. 11:12 says "From the days of John the Baptist until now, the kingdom of heaven has been subjected to violence, and violent people have been raiding it." Are we to assume that the kingdom heaven is still subjected to violence today?
Matt. 13:33 says "The kingdom of heaven is like yeast that a woman took and mixed into about sixty pounds of flour until it worked all through the dough.” Are we to assume that she continued to mix it in for the rest of her life?
Matt. 16:28 says "Truly I tell you, some who are standing here will not taste death before they see the Son of Man coming in his kingdom.” Did they never taste death even afterwards, such that they never died at all?
Matt. 17:9 says "As they were coming down the mountain, Jesus instructed them, Don’t tell anyone what you have seen, until the Son of Man has been raised from the dead.” Were they not supposed to tell anyone abut it even afterwards?
Matt. 23:39 says "For I tell you, you will not see me again until you say, ‘Blessed is he who comes in the name of the Lord.’" Did theY never see him again even after so stating?
Matt. 24:34 says "Truly I tell you, this generation will certainly not pass away until all these things have happened." Even after they happen, are we to understand that this generation will not ever pass away?
Matt. 26:29 says "I tell you, I will not drink from this fruit of the vine from now on until that day when I drink it new with you in my Father’s kingdom.” Does this mean he will never drink it new, ever?
Matt. 27:45 says "From noon until three in the afternoon darkness came over all the land." Did darkness stay over the land beyond three in the afternoon?
AS YOU SEE FROM THESE VERSES, "UNTIL" IN MATTHEW OFTEN CARRIES THE CONNOTATION "BUT NOT THEREAFTER." PERMANENCY IS NOT IMPLIED.