Well, my opinion to the whole thing: She would still commit suicide. For me this was in a way suicide, I mean... SHE SMILED when she falled O.O In a delented scene it was even suicide, but the gusy from SP changed it, becaus eit was too "dark" -.-' Anyway, suicide just fits SO good in her crazy mind, it would be perfect. And I just can't imagine that Zira would really join Simba, I mean she devoted her whole life in killing Simba and if I would be her, after so many years, I would NEVER just forgive everything

Yes, I think she would fight till the end.