USBC is a golden example of "good" regulation. Thank you EU!
Do you think USB-C will be around forever? Hint: it won’t. And then all those cables will go to waste.
I'd wager that a large majority of iPhone owners already have USB-C cables from some other product. But even if there is a small increase in wasted cables for 2-3 years as people acquire new cables, it will easily be offset over the next 5-10 due to reuse across multiple products.
At this stage it's genuinely hard to envision something replacing it - they're pulling 40gbit over this connector, running full pcie, displayport, etc. Most devices including these new phones are still using USB 2 speeds because it's good enough.
And if the phones are going in the landfill, the cables are a rounding error.