Arguably, moving services to the cloud is going to be only a little different from when you manage the services locally.  You're still going to have to keep track of that one reporting server that only gets used once per quarter (or worse, once a year,) but then spends the remainder of the year idle.  The difference being, with an on-premise, you'd probably just leave the box on and eat the costs of electric, cooling, patching.
With a cloud server, you might shut it down to avoid paying charges for it.

But what about the process some developer stood up in the cloud, for a very particular use-case, but it never got documented?  That's your cancelled service contract disruption waiting to happen.

Over time, I think as funbi and Dalkeith said, organizations will have someone assigned to monitoring the cloud service bills for anomalous charges, tracking down why there's certain charges (oh, that service?  Yeah, Joe stood that up a couple months ago for the developers, but I don't know if they ever used it and Joe left a month ago,) and in general riding herd on the cloud services.  Smaller companies, this might fall to the DBA or developers, with a dash of the accounting people thrown in.

Short term?  Yeah, I can see companies finding services they'd been paying for, for months, but weren't using because some developer stood it up and forgot about it when they were done.