According to IBM United States Withdrawal Announcement 905-163 (Changes in support for IBM OS/2 Warp 4 and OS/2 Warp Server for e-business) issued on July 12, 2005:
Effective December 31, 2006, IBM will withdraw standard support for the following products licensed under the IBM International Program License Agreement. Fee-based service offerings will continue to be available. These offerings will provide support beyond December 31, 2006, via a services contract. For information about the extended support offering, contact your IBM representative.
Program Program Support
number name withdrawal date
5639-A29 OS/2 Warp(R) 4 12/31/06
5639-F93 OS/2 Warp Server for e-business Version 1 12/31/06
In addition, IBM will withdraw from marketing selected OS/2 Warp parts. Refer to Description for details.
Replacement information: None.
I've attached a copy of the notice to this post.