You would have to be huge for Windows to entertain support for NT4, for starters hardly anyone at Microsoft who works in support will have been there in the NT4 days.
2000 has "only" just gone out of support so not so difficult, and it's similiar to 2003 anyway.
To be honest why the hell would any organization want to use NT4? Using XP is bad enough when you compare to the huge management benefits you get with Windows 7.
Whatever, if they want to waste money on resources supporting old software then they can do.
The trouble is perhaps human issues, people who run the networks cant cope with change, don't know about better ROI of newer products, etc. Too much legacy software. List goes on, often a lot of reasons you see for not being able to upgrade were due to incompetence or bad decisions in the first place
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