Indeed! Missed that, thanks! 
That is a common concern, yes, but we have the advantage in:
- that the changes won’t be that great and will remove only obsolete functionality which has no room in a modern language any more, allowing all modern packages, libraries, CMSes and frameworks to function as usual
- the community is much greater and far more involved with the lower level stuff in PHP (many are at least dissecting frameworks, if not building their own) so the manpower to convert those few packages that people actually use but which still won’t be able to digest PHP7 is more than present.
The only problem might be extensions, but even that will be largely taken care of by both the community and those extension developers whose extensions are still being actively used (most of them still keep an eye on them and keep them up to date).
I don’t think we have anything to worry about. With good repositories such as sitepoint.com/php adopting PHP7 from day 0 and pushing out good resources about adoption and using the new version properly, I don’t think we’ll have much to fear. It’s just a matter of reaching those who are still in the dark, and that’s something everyone is already trying to do.