Why are traditionally Republican newspapers endorsing Hillary is this some kind of conspiracy?

Because as the editorial staff has changed the newer editors have been raised on the Liberal Pablum .

The Editorial Staff and management at a newspaper is separate from the business side of the paper [ the producers ] .
So while the Lefties are now in control of Editorial papers are going out of business in droves with plenty more to fold over the next few years . Even the giants are bleeding money like it was printers ink .

No one reads them anyway. They are all losing money. Let them fail.