if he does leave the embassy, the most likely scenario seems to be that the brits arrest him and he is extradited to the US.
I'm not sure what the difference between wikileaks and the Pentagon Papers
In 1971, Daniel Ellsberg leaked government documents that showed that JFK and LBJ had lied about why they went to war in Vietnam (the real reason was to contain China). Ellsberg worked for RAND and xeroxed the documents. Ellsberg and a co-conspirator were charged, but the press were allowed by the supreme court to publish the documents
Only a free and unrestrained press can effectively expose deception in government. And paramount among the responsibilities of a free press is the duty to prevent any part of the government from deceiving the people and sending them off to distant lands to die of foreign fevers and foreign shot and shell.
— Justice Black
Is publishing documents on the internet the same as publishing them in a newspaper?