I don't know, why you want to rewrite the whole PHP core? As far as i know, with PHP 7, a bunch of brilliant guys are working on it, right now! Nobody has to rely on one companies work, because this is an Open Source project and all developers out of the PHP universe can be a part of it. When you talk about hundreds of developers that support Gearman, RabbitMQ ... so this project, as of its PHP nature, has the potential to be supported by millions of PHP developers out there ;)
I was speaking of rewriting the core of existing PHP platforms (e.g. Drupal, Wordpress, Magento) not PHP itself. To gain benefits, that could be offered by this product, a whole lot of modifications would need to happen. So not only as a responsible dev but also from a mangers point of view, it'd be risky to rely on an experimental work instead of a variety of tools that can offer me same if not more (Gearman / RabbitMQ: use nodejs for faster image processing, java for stable PDF rendering, what so ever).
Furthermore this seems to be a company's product instead of a foundations joint work. We all know that every company has a certain monetary interest in the things they produce. At some point they might want to monetize the product or parts of it and boom - you're screwed. Sitting right there in the vendor lock. And at that point it doesn't even matter if it's "open source". I don't trust these guys.
