The first longer answer is that work is under way in ANSI to determine what will be happening to this material from HITSP. A communication will be made to HITSP members before the expiration of the HITSP contract with ONC. I expect to hear something soon from ANSI/HITSP leadership on the status of the web site. Given that there are current activities supporting meaningful use making use of these specifications, including the NHIN Connect project, I do not expect them to disappear from the web.
The second answer is supported by the copyright notice appearing in all HITSP specifications and appearing below:
COPYRIGHT NOTICEThis indicates that the specification can be posted in their entirety on another web site. I have already downloaded all current specfications, and many prior versions from the HITSP web site. If nothing official happens through ANSI, I promise they will become available from another location.
© 2010 ANSI. This material may be copied without permission from ANSI only if and to the extent that the text is not altered in any fashion and ANSI’s copyright is clearly noted.