They're proposing essentially that: start at the 24th slide http://www.slideshare.net/zerutreck/taking-php-seriously-kei...

The smart part is that it's opt-in so you could gradually migrate a large project in-place. The only question would be whether they've broken compatibility with standard PHP or if it's simply stricter — it'd be really easy to get major projects to switch if it was like JavaScript's "use strict" where you can develop in strict mode but run on a legacy runtime.