Isn't it just common sense? The provisioning / capacity planning for a DC has to be done based on peak usage. The usage patterns of the core business and the hosted customers are almost certainly going to be the same -- there's going to be a trough in the night-time, and a peak in the evening. At the time when people want to buy resources, you'll have no spare resources to sell.
The only way the business model of selling spare resources could work is if you found customers with a different usage pattern to fill the trough. That's hard.
Yes, you can find some customers with time-insensitive batch processing that could be done during the night time. But Google and Amazon already do massive amounts of batch processing, and still won't have a flat utilization level over the day.
Or alternatively you could try to flatten out the diurnal variations by making sure there's no geographic affinity between users and the DCs. But that's suboptimal given intercontinental network latencies.
The only way the business model of selling spare resources could work is if you found customers with a different usage pattern to fill the trough. That's hard.
Yes, you can find some customers with time-insensitive batch processing that could be done during the night time. But Google and Amazon already do massive amounts of batch processing, and still won't have a flat utilization level over the day.
Or alternatively you could try to flatten out the diurnal variations by making sure there's no geographic affinity between users and the DCs. But that's suboptimal given intercontinental network latencies.