I don't know how I missed this, it should've been hyped. But here it is: an Amazon truck trailer, which is basically a giant Snowball, used to overcome the data inertia. Apparently, its capacity is 100 PB (the article is not clear about it, but it mentions that 10 Snowmobiles transfer an EB). The service apparently works one way only: you cannot use a Snomobile to download your data from Amazon.
P.S. Amazon's official page for Snowmobile confirms the 100 PB capacity.