Is the system broken?

As the voting starts, what will happen if Jeremy Corbyn wins again?  It's difficult to see how those MPs who voted for a motion of no confidence in him as their leader can stay under those circumstances.  So what do they do?  Walk away?  Set up a new party (shade of the SDP)?  Hunker down and continue the fight?  Whatever happens, it is difficult to see any future for the party as a serious opposition, and that's worrying.  Our parliamentary system requires a strong opposition to hold the Government to account, and at present we haven't got that, and signs are that we're not going to get it any time soon.