Microsoft has announced the Windows NT Server 4.0 Retirement Cycle schedule:
October 1, 2001 Product: Volume licensing no longer available for Standard and Enterprise editions of NT Server.
July 1, 2002 Product: Reseller channels can not sell Standard, Enterprise or Terminal Server.
January 1, 2003 Support: Microsoft will charge a fee to customers requesting non-security Quick Fix Engineering (QFE) hot fixes.
July 1, 2003 Product: System builder channel can not sell Standard Edition.
January 1, 2004 Support: Pay-per-incident and premier support for Windows NT Server will not be available.
I doubt they will be able to drop support for NT server but we will see.
I will use this page for Windows NT Server Retirement info. If you haven't started on a migration plan to Windows 2000, check the above schedule and consider how much time you have left.