However it neglects to include Backblaze's B2 storage which is only $5/TB/month - https://www.backblaze.com/b2/cloud-storage-pricing.html
That is maybe a not a big enough price saving to convince conservative corporations to switch. Imagine going to your accounts department to request they purchase a cryptocurrency so you can use it to pay for data storage.
Amazon S3 also offers "glacier" for longterm storage with few accesses, which is $4 per TB.
It's best not to use Glacier as a price comparison because it's really misleading.
If you're just looking for storage, S3 is certainly not the cheapest provider. Glacier is a bit different but clearly just for archives.
As for bandwidth cost: I don't believe Sia can be successful and stay that cheap. Why would providers of bandwidth for Sia be able to offer it magnitudes cheaper than the biggest tech companies in the world? Answer: It's offered by a bunch of individuals with no caps on their data plans. If Sia takes off and lots of people start using terabytes of bandwidth, the ISPs will put an end to it.