http://www.tms.org/pubs/journals/JOM/matters/matters-9107.html

The reissue route cannot be used to introduce new matter into the patent. The claims sought in the reissue must fall within the invention as described in the original patent. If the reissue seeks to broaden the claims, the application for reissue must be flied within two years after the date of grant of the patent. If the reissue seeks to narrow the claims, the application can be filed at any time prior to expiration of the patent. The reissued patent will expire 17 years after the date of grant of the original patent.

Any entity knowingly infringing after bring official notified by the patent holders will pay retroactively for infringement prior to the patents expiration. So it won’t make much difference if they expire next week. If the patents hold up all 450 companies on notification will pay or go to court and pay