As far as I can tell, ISC did not say they would stop distributing patches through the same methods used now. If you don't want to pay, you will get the exact same patches, through the exact same methods you get them now. Which is pretty good for "free" software. If you get BIND via a vendor distribution, such as AIX, Solaris, OSF/1, Redhat, etc; your support channels will not change.
I suspect the reality will be those companies paying ISC for "advanced notice" will get some warm fuzzy feelings, and let management feel they've done something. But it doesn't alter the fact the software had a vulnerability, and someone else could have found the hole long before any advanced notice is issued by ISC. How many folks will now query the root-name servers CHAOS version numbers looking for a change.
A couple of points on these issues: 1) Noone has suggested that the current public distribution would go away. What has been a point of concern is that the public may have to wait [too long?] for vendors to get their act together and publish patches before the new release hits the general distribution. A good many companies don't rely on vendor patches. 2) Advanced notice has been called "paranoia" and "warm fuzzy". What it really is -- is the opportunity to have a bit of time for planning instead of engaging the gears for emergency mode.