Quick post, a new application of a small part of a long piece I composed far away and long ago.
10:8 בָּעֵת הַהִוא, הִבְדִּיל יְהוָה אֶת-שֵׁבֶט הַלֵּוִי, לָשֵׂאת, אֶת-אֲרוֹן בְּרִית-יְהוָה--לַעֲמֹד לִפְנֵי יְהוָה לְשָׁרְתוֹ וּלְבָרֵךְ בִּשְׁמוֹ, עַד הַיּוֹם הַזֶּה.
Rashi: To carry the Aron - [referring to] the Leviim. To stand...and bless - [referring to] the Kohanim [who bless the people], and this refers to duchening.
Rambam, Sefer Hamitzvos Aseh 34, says there is a mitzvah for the Kohanim to carry the Aron on their shoulders. He says in the early years Leviim carried it because there were not enough Kohanim to do so, but the mitzvah was really for the Kohanim. He makes no reference to any other vessels of the mishkan. In fact, in Shoresh 3 he does not count the age limitation of the Leviim as a mitzvah because he holds it is not a permanent mitzvah; Ramban there argues vociferously on the Rambam for several reasons. Brisker Rav (al Harambam, second letter in the back) wrote to Rav Yoshe Ber ("Yakiri") about this. He says that Rambam is not talking about the Aron of the mishkan/mikdash at all, but of the "first" Aron that Moshe built before the Mishkan - pasuk 3 of the same Perek - a wooden Aron, and that was the Aron taken to war. This Aron was carried by the Kohanim, and it was not related to the mishkan and was thus not a temporary mitzvah which ended when the Beis Hamikdash was dedicated.
Thus the Rambam will learn this pasuk as talking entirely about the Kohanim, and they are called Leviim because they are indeed part of shevet Levi. In fact, the end of the pasuk says "ad hayom hazeh" to tell us the mitzvah to carry the Aron is a permanent mitzvah (even though the source of the mitzvah to carry the Aron on the shoulders is "bakasef yisa'u).