It might, arguably, be "not over" if Bernie were polling at something like 70% in California. But he's not.

The delegate deficit he has right now (four times what Obama had over Hillary at the end of 2008, from what I last heard), means that coming in close or doing "better than expected" counts for nothing.

In fact, unless he turns around a few hundred superdelegates (which he's failed to do so far), it looks like the California result won't matter for anything anyway. Hillary will have the primary numerically tied up immediately after the New Jersey results come in. And again, this is even if Bernie wins New Jersey.