This is in the News for Ecomm Sellers category because it might disrupt several online sales channels with POD, not just Amazon, especially given how embedded Alexa is in many US homes.
I suspect that it could result in purchases Amazon wouldn’t have otherwise, just due to the ease of it and the integration with Alexa.
And then also shoppers who are experienced with customizations but don’t like the downtime/back-and-forth with online or in-person t-shirt designers will jump on it, telling themselves that it’s the same quality but fastet.