What are you trying to suggest? That the Taliban are going to disregard Iran's concerns or worse, choose to pose a threat to Iran? No, they won't, because that would imply Iran throwing her full weight behind a host of factions that have issues with the Taliban, and Afghanistan being the relatively fractured society it still is, and Iran having experience in establishing networks of allies there since the war against Soviet occupiers in the 80's, this is what would occur.
However, that's not what the Taliban want. They're not interested in another three or four decades of war either. Which is why they've made all these overtures towards Iran and have given Tehran concrete assurances on what matters most to Iran, namely:
1) Not to create any direct security threats for Iran.
2) Not to host nor support any anti-Iranian terrorist proxies either.
3) To try and find a political power sharing understanding with Iran's local allies, instead of fighting them.
4) Not to think of harming Afghan Moslem Shia civilian populations.
5) Cooperate with Iran against "I"SIS-K.
And if you believe Russia is going to easily allow a regime to take over in Kabul that is hostile to Moscow's interests, then you're the one having delusions. And that too, the Taliban are aware of. Hence why they are mindful of not "crossing" Russia either.
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The total of legal and illegal Afghan residents in Iran, is actually as high as 4 million. That's slightly more than 10% of Afghanistan's population.
Those with little to no knowledge of the Afghan issue seem to be stuck in the 1990's, believing this is a zero sum game between a supposed Pakistan-Taliban axis and the rest. In reality, none of the sides is under the delusion that anything but power sharing will be possible barring many more years of war and instability that will risk spilling over borders - which thankfully, none of the actors with a direct stake in this wants.