Should Corbyn go now before he can attempt to ensure his replacement follows his disastrous policies?

Ideally. Yes. But a narcissist like Corbyn believes that HE IS the Party.

His replacement will be chosen by the 500,000 members of the Labour Party, following party laws and proceedures to replace the leader.

If you think vowing to save the NHS, restore police numbers, ensure the most vulnerable in are society are treated fairly stopping the slashing of funding to our schools and that mega corporations and the richest in our society should pay their fair share of taxes etc., are disastrous policies, then you will be disappointed in who the party pick to replace Corbyn.

Matters, not... FIVE years in the wilderness for the Party, for whoever is leader.......

Maggie Thatcher enjoyed 11 years as PM because Michael Foot was the unelectable leader of the Labour Party.  At the last Labour leadership election, anyone could vote if they paid £3.  The Tories saw their opportunity and bought enough votes to get another Labour leader who would keep them in power.  Corbyn has done his job.  Now he should enjoy a well-earned retirement - I'm sure Boris will be grateful enough to find him a seat in the Lords.  Next time, Labour, don't sell votes or you'll be out of power for the foreseeable future.

It really is  matter for the Labour Party -- it is up to it's members to fight for the party that they want .

I don't think Corbyn ever wanted such a public roll as Leader or Prime Minister -- he just wanted the power to move policy his way .

He would have preferred to be the power behind,and manipulating  the "Leader" --akin to Putin ,when he let "his" deputy become President for a term .

Corbyn ,and his "brown shirt" Momentum followers ,will grapple and scheme to keep  power behind the scenes : I suspect there will be some brutal in fighting, in the Labour Party, behind the scenes, which the will hide with an all out attack on any Conservative policy . .   

He has already said he will  stay on to "oversee"  the transition period. 

Translation:   Oh dear God!!!!! Don't make me GO!!!!!  NO!!! NOOOOOOOO!!!!  I don't want to lose my seat and all my power!!!!  WAIT............I can still lead!   Really, I can!   Just give me 10 or 15 more years!!!!!!!!  You'll see!!!!!!!!!!!!!