Here's a story of an unlikely marriage of the .NET Framework and green screen terminals. CO-OP Financial services, an electronic funds transfer network, moved their core app off the Mainframe, and to a Windows Server, to save costs. They reduced their yearly maintenance cost from $2.3 Million to .... virtually nothing. Basically they had a $18,500 switching cost, which was less than the monthly ongoing maintenance cost for the mainframe. For ongoing costs, the monthly license charges associated to the mainframe software disappeared, and system maintenance was absorbed into existing staff. CO-OP Financial used the lift-and-shift approach, moving COBOL code from the Unisys mainframe to a Windows Server using Micro Focus Net Express (a COBOL environment which utilizes the .NET Framework). But, they did not want to disrupt the existing users of the app, who continued to rely on green screens. Generate green screens via .NET apps? You betcha.
A couple of key Microsoft partners were involved: Micro Focus, and system integrator Progeni.