Do a search on this topic, it has been done to death.
The answer is that given how the plot had been screwed up by Goering and Himmler not being present on the 20th, plus a variety of problems with the coup after the assassination, likely there is a civil war of some duration. Germany was beyond saving by this point, so it is just a question of making the war end sooner, which will happen one way or another if Hitler is assassinated successfully.