Any active judge can ask for an en banc vote (to determine if there will be an en banc hearing), in which only the active judges vote. If the vote favors an en banc hearing, 10 active judges are chosen at random to join the (current) Clinton-appointed Chief Judge to hear the case en banc. So to have a strong chance of having a favorable outcome, the random 10-judge draw would have to come up 6 R-appointed and 4 D-appointed.
What you are saying is we are likely to lose at the en banc ruling and the SC will not take the cast. This ruling just gives California citizens a few weeks to buy 30 round magazines.