The big difference between Red Hat and a lot of these other companies is that if you look at a lot of their products, including the cash cow (RHEL), there is no

The big difference between Red Hat and a lot of these other companies is that if you look at a lot of their products, including the cash cow (RHEL), there is not a 1:1 mapping between the product and a single open source project. Rather they create enterprise distributions that are made up of a number of open source projects that are (ideally) integrated into a solution. This combined with the right investment in support and training provides a product that is more compelling than "we provide a signed version of $UPSTREAM_PROJECT". I would say OEL is successful for the amount Oracle appear to invest in it (not much). Timing helps a lot too though, in that they had a lot of success before the advent of the public cloud so are in a better position to weather the storm while they figure out a new model.