Well, the White House press corps has already been changed to (how do I write this in a way that won't get me downvoted?) include more reporters friendly to the current administration since the White House asserted the right to determine itself who gets access (formerly it was the White House Correspondents' Association), so the chances of such a more-or-less unified boycott are slim. And I don't have any doubts that the Pentagon will also quickly find enough "warm bodies" (besides those from OANN) to prevent an embarrassing almost empty room at the next press conference...