Exactly. Killing off the main character would make no sense. Unless Kathleen Kennedy stepped in and said, "Enough of this wildy successful foolishness. Kill off Mando and make Bo Katan the lead." Wait a minute, that's actually plausible.
Let's hope they have sense enough to not destroy the heart of this show which is the relationship between Mando and Grogu. Without that it would just be a show about Mandalorians fighting the Empire, which is cool and all but it would no longer be The Mandalorian.
Of all the rumors I've seen the most compelling is Mando having his mind wiped and fighting for Gideon. That would be devastating but it would make for a great story.