I am not sure of all the ins and outs of the Labour Party but I did think that those in momentum and the unions, and the Labour MPs, each has a vote Annie.
It sounds as if the unions may be going in the right direction - whatever the outcome - as, from your analysis they didn't have MPs who actually represented the majority.
It will not all be about Labour though, although I appreciate this is a thread on that. What will happen if, in the end, we don't get the leave arrangements Johnson has promised, or don't get sufficient trade deals with other countries, or working practices do turn out to be worse? Before this is all over the current ERG Conservative party could have changed. Johnson calls himself a "one-nation" Conservative but threw others, who saw themselves like that, out. What if the Conservative Party splits? What if we get PR?
The only thing any party can do is stand on the principles it believes in. You left the party that stood for the person who lives only on the income from his work Annie. How can anything else be called "Labour".