Albert Barnes Commentary Jeremiah 3:16

"And it shall come to pass, when ye are multiplied and increased in the land, in those days, saith Jehovah, they shall say no more, The ark of the covenant of Jehovah; neither shall it come to mind; neither shall they remember it; neither shall they miss it; neither shall it be made any more." — Jeremiah 3:16 (ASV)

In those days - This and the phrase “the latter days” had become, under the Messianic teaching of the prophets, a regular formula for the time of Christ’s coming, when all the nation’s hopes would be fulfilled.

The ark was the center of the Mosaic economy, containing within it the two tables of the Law as the conditions of the covenant, and having over it, upon the mercy-seat, the Shechinah as the visible sign of God’s presence. But “in those days” the symbol must pass away, because God will then dwell in His people by the gift of the Holy Spirit (1 Corinthians 3:16), and the terms of the covenant will be written on their hearts (Jeremiah 31:33).

Neither shall they visit it - Rather, neither shall they miss it; that is, they will not trouble themselves about it, nor regret its loss.

Neither shall that be done anymore - Rather, “neither shall it (the ark) be made anymore;” it shall not be renewed or repaired, because the tabernacle of God will be one “made without hands” (Hebrews 9:11), even the heart of His believing people.