That not what I got from it. When Ganondorf was weak Zant seized the opportunity and used some magic (not sure if it's interloper or ToP magic) to steal the ToP and kill Ganondrof
It's impossible to steal Triforce pieces; this is a fact.
It starts with Ganondorf talking about how it isn't the end but then he unexpectantly looses the ToP, the symbol fades from his wrist and the sound of a machine shutting down is heard. We then see Zant, who is perfectly fine, we then see Zant crack his neck, which would appear to be some sort of spell, which kills Ganondorf. There is no evidence of Zant ever dieing.
What the hell kind of bizarro universe do you live in where SNAPPING YOUR NECK means casting a spell, and not dying? Because when someone's neck snaps, they instantly die. Just like Ganondorf...instantly dies. Zant can live as long as Ganondorf lives, but he can only live as long as Ganondorf is alive. That's their tradeoff.
Your reasoning why Midna shattered the mirror does not make a lot of sense, Zelda explains in an interesting speech of why the mirror was left in Hyrule and why it should be kept there. Then Midna shatters it, which would completely contradict everything Zelda just said... However if Zant obtained the ToP, like it is implied, he would be a grave threat to both the Twilight Realm and Hyrule. Midna destroying the mirror would stop Zant wreaking havoc again, she would not put Hyrule at risk and allow history to repeat itself. Breaking the mirror would assure Hyrule's safety.
How in the hell would Midna even know about Zant? And why not simply tell Link this, and go kick his ass? They've done it before. Hell, Ganondorf demonstrates that the Triforce of Power allows him to travel the realms without needing the mirror, so destroying the Mirror wouldn't stop Zant whatsoever.
Your idea is complete and total crap, dude, sorry.