We operate staking nodes on certain blockchain networks utilizing customers’ crypto assets and pass through the rewards received to those customers, less a service fee. In other cases, upon customers’ instructions, we may delegate our customers’ assets to third-party service providers that are unaffiliated with us. Some networks may further require customer assets to be transferred into smart contracts on the underlying blockchain networks not under our or anyone’s control.
...probably moot if these "third party service providers" are just doing the busywork of interacting with the protocol, on behalf of Coinbase, on behalf of the user. I grant that this involves a kind of custody management you don't see in other non-securitized IT services, but as long as everything is spelled out clearly (which it seems to be in the excerpt you posted) I maintain my position.
That it's not a loan or it's not a security? Or both?
I guess my final question is: do you think there is any risk to a user of those third party service providers going under and not returning capital (either due to slashing risk or normal business risk)?
Of course, but it's more like an email provider going under and you losing your inbox than a bad mortgage (which isn't to say that it's exactly the same, because blockchain assets are practically treated as currency, but clearly doesn't map onto the traditional understanding of securitization).