I think the plan has to be more than just “don’t attend” the pressers. If CBS/NBC/ABC/CNN/WSJ/NYT/etc/etc/etc do not attend, no one except the die hards will notice.

1) All the Fox News/Breitbart/etc/etc “journalists” will be in attendance and report.
2) All the credible outlets will still report (it is news).

If they choose not to attend en masse then they need to editorialize their front covers and news broadcasts to let the public know why. THEN get to the news.