I am SO down with it remaining a slur, and for not purely sectarian reasons.
While the article above does a good job of problematizing what the term “progressive” really means, I think the term does a good job as a euphemism for an alliance of folks on the left. From communists and some anarchists to non-explicitly-ideological folks like Glenn Greenwald and Amy Goodman. Euphemistic as it is, I believe it is a good rhetorical tool for folks to play with. As in a previous discussion, naming one’s self and one’s movement creates a certain sense of solidarity even across ideological lines.