It has everything to do with Sanders since he is the only person with enough pledged delegates to even try and enforce a full floor vote. If he doesn't do it then no one else will because the rest of the Dem Party is all in with Hillary.
Your idea of the party just handing the nom to Joe Biden is almost too stupid to even entertain but fine: After the first floor vote Hillary will have enough to be declared the nominee and no one else will be even mentioned. So to anser the question you posed in the title of this thread...Hillary Clinton comes out of the Democratic National Convention as the nominee.
