What do we learn from "v'Hayah cha'Am ka'Kohen"?
Rashi: I will equate the nation for disgrace like these who profaned them from being a Kohen to them. Therefore, also I will profane the nation amidst Nochrim. Yonason translates like this.
Radak: This equates each to the other. Verses speak like this ? "Ki Chamocha k'Far'o" (Bereishis 44:18), "ka'Malveh ka'Loveh" (Yeshayah 24:2). Just like the nation and Kohen are equal in sin, they will be equal in the punishment.
Malbim: The nation will sin b'Mezid, for the Kohen teaches them to do evil deeds like himself.
Why does it say both "u'Fakadti Alav Derachav" and "u'Ma'alalav Ashiv Lo?
Malbim: I will punish him for his evil ways, and 'pay' him Midah k'Neged Midah.