Re: "Once upon a time, Microsoft's cloudy storage was unlimited"
The problem with "unlimited" in relation to storage space is that there's no real (sensible) upper limit
Things like mobile phone contracts can offer "unlimited" voice, knowing that even if you talk for 24 hours per day, there's a hard limit of ~720 hours in a month. Likewise, "unlimited" data is limited by the transfer rate, and this can always be manipulated by the telco in order to keep things within flexible boundaries. In both cases, after the initial cost of infrastructure has been covered, it's all about sending packets of data, with no additional hardware resource.
The problem with offering unlimited storage has always been the fact that this storage capacity has to translate into physical disks or SSD's somewhere along the line, and so your hardware requirements will have to scale in line with the needs of your customers.