The other part of the equation, software aside, is risk - Anyone using mainframes heavily in the way we are talking about here is probably running something mi

The other part of the equation, software aside, is risk - Anyone using mainframes heavily in the way we are talking about here is probably running something mission critical with lots of $$$ tied into it - and the financial/legal risk of having anything go wrong at all is a huge driver - they want a big company with deep pockets and pages long support agreements backing them, so they can indemnify the other company if there is any problem and shift the blame (and from a personal perspective, cover their own butt). The mainframe using companies also usually have deep pockets, and so even if the mainframe is expensive, it still allows them enough profit margin to support it.. "There is a problem with our IBM mainframe, we have requisitioned a team of 12 people from IBM to investigate and legal is looking into what sort of contractual obligations IBM has if issues aren't resolved" is a much more palatable statement for the fortune-100 CIO to pass along to the CEO than "our IBM emulator seems to be having problems, but the 3 people developing it are on vacation, IT isn't sure if it's an emulator issue or something to do with the new hardware we migrated to run it on 2 years ago, and IBM says they don't support the software when it's run on the emulator. We're calling them again to see if there's some way we can convince them otherwise"