The parallels with Clara though. Like it starts with Bill not realising she is a cybermen and blocking it out like Oswin in ‘Asylum of the Daleks’. And then the ending with Heather saving her. Bill is immortal and her last lines about travelling in time for tea is similar to Clara’s ending in 'Hell Bent’ with her being like the Doctor.
I’m so sad to see her go but like Clara, she lives on with her own companion.