I know that IBM is masterful at bundling software or selling its customer base enterprise software licenses. When I worked there, my division could trace a hug

I know that IBM is masterful at bundling software or selling its customer base enterprise software licenses. When I worked there, my division could trace a huge piece of its revenues (and profit) to a mainframe monitoring app that basically had no competitors. All the divisions other stuff got thrown in basically for free. Thus the idea of the "IBM shop" - customers who were big blue all the way. "No one ever got fired for buying IBM." I don't know about the difficulty of migration - what I always understood (and I later worked at one of the largest financial institutions in the US) was there was tremendous investment by the companies running on mainframes in the software developed to run on mainframes. And that these companies weren't interested in migrating to newer hardware/software combos because it was kind of murky if the cost effectiveness of such a move could be reasoned about. These are also the types of companies least interested in losing control of their data. They aren't interested in the cloud for even their non-mainframe apps. To be fair, the financial company I was at maintained its own data centers, so it might be too atypical to draw any meaningful conclusions from my experience there.