I know this doesn't answer your question specifically, but if you have a site and a product already launched, and if it is working, why change to just to accommodate a single person. Not to knock him or his skills, but that seems like spinning wheels when you could be out selling and improving.

Now if the site is not developed and you do not have a product, I would say do whatever you are most comfortable in to get it launched. There will always be the next great language out there and to second guess yourself now is just wasting valuable time. PHP, while it has its moments, is not a bad language to build a product with. There are plenty of big name sites that got their start as PHP or are still built on PHP. I highly doubt that in the next few years that PHP developers are going to be a thing of the past.

I've been developing for about 18mths and built the MVP in Django. The site has decent traction and user feedback has been incredible. But, in order to get the product to the next level I need to take a backseat when it comes to the development and focus on marketing (my primary skill set).

Migrating the site to php would be trivial, the codebase is pretty basic. The technical requirements of V2 of the product will far exceed my abilities as a developer.

He also has extensive CTO experience and just all around is the kind of developer that can take the company to the next level...

PHP is going through a technical renaissance and does not deserve (some of) the bad rep it has: http://radar.oreilly.com/2014/03/the-new-php.html

The community is huge and there are plenty of mature software and components to use. I would not be shy of using PHP and wouldn't worry about hiring challenges in the next few years.

That said, I would not hang my business on a single technology. Building with a combination of PHP and Node.js should be a good bet as these compliment each other and will provide developers chances to learn new things.

Interesting, I know next to nothing about the php community. Appreciate your advice!

I can't talk for others but according to my experience I found that getting high quality Python/Django developers is much easier than PHP. Someone would expect the situation to be the other way around due to the larger PHP pool, but it's not.

Funny you say that because I built the current site in Django. This is definitely my fear!