In the recent past, I've had the opportunity to speak with representatives of Cobol-IT, Compuware, Heirloom Computing, TmaxSoft and a few others who have targeted enterprises still using mainframes.
A few of them, such as Compuware, are focused on adding rapid application development and deployment (aka DevOps) to the mainframe, making the environment seem relevant today.
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Most of the others, however, are focused on convincing enterprises that it is finally time for them to abandon the mainframe and move those workloads to industry-standard x86 systems running Windows or Linux or, perhaps, to midrange Unix systems.