Was Zira's only SOLID plan to kill Simba for revenge?

[FriendlyHyena]

I know I mentioned my "Zira planned to make Kiara marry Kovu so that she'd get the throne that way" theory in another thread, but one of the issues with Lion King vs Lion King 2 is that Scar had a definite plan:

First it was to try and get the hyenas to kill Simba and Mufasa in the Elephant Graveyard.
Then it was to kill Simba and Mufasa in the Stampede.
Then, when Simba survived, it was to have the hyenas finish off Simba.
In short, Scar had a definite plan to take over the throne itself (it was his plan of what to do AFTER taking over that seemed rather weak as to make one wonder why neither the lionesses nor even the hyenas had staged a revolt some point before Simba had shown up.)

Zira, however, appears to not show what she intends to do once taking over nor does she show how she intended to secure the throne once Simba was dead. Of course, it's possible that her main goal in life was to kill Simba and that everything else was just an afterthought that could be winged later. It would explain a lot, including why she'd basically try and kill Simba all by herself in the final battle.

I wonder if she was, somewhat, similar to Gaston from Beauty and the Beast. He originally probably did really have as his main goal to marry Belle, but as things got harder, I think his blackmail attempt with the insane asylum was the final attempt to get her to marry him. Once Belle had proven her father to not be crazy by showing everyone that the Beast existed, that plan was ruined, and his goal for the rest of the movie was to kill the Beast, which it seemed he had done right before falling to his death. Interestingly, in an earlier version of the film, Gaston stabbed the Beast fatally in the back before leaping off the roof, laughing, to his own death. Similarly, in an earlier version of Lion King 2, Zira actually let go and fell, possibly laughing, to her death, when her final attempt to kill Simba failed.

However, Zira almost seems closer to Roger Chillingsworth Prynne from The Scarlet Letter, who seemed to exist only in the story to torment the Reverend Dimsdale, and when Dimsdale died near the end, he seemed to have lost his purpose in life and died some time shortly thereafter.

I guess that the only other argument I can think of that sounds somewhat plausible as to Zira's plans to take over the Pridelands, if my earlier suggestion about a forced married between Kovu and Kiara wasn't the answer, is that Zira DIDN'T have a real plan to take over once Simba was dead. Her whole goal, whatever she told the others, in life was to kill Simba, to get even for all the wrong she felt, and that she was willing to sacrifice her children and even herself to reach that goal.

Also, if you look at it from that angle, then not only was Nuka neglected, but Kovu was also horribly mistreated, as Zira seemed unconcerned if Kovu would make it out of the Pridelands alive even if his assassination attempt worked (especially the one where Kovu was supposed to go into Pride Rock and kill him (like he'd get out of there alive even if the plan succeeded!)

I think, if this other theory holds up, that Zira pretty much was just focused on killing Simba, that Vitani kept thinking the whole thing was for a better life and to get back into the Pridelands. Once that was offered by Kiara and yet Zira still kept at it, I think at that point, Vitani truly realized what her mother was REALLY after and didn't want to go along with it any further.