PHP has only one feature going for it: it already exists. As soon as you introduce a new programming language, you lose what PHP has to offer. Another success is the lack of a library culture -- just copy-and-paste code into your app, and you never have to worry about installing dependencies on your shared host.

If you want a better version of PHP, try Perl / Python / Ruby. If you want a language that can check your code for safety at compile-time, use Haskell. But if you invent your own language, it will have three problem: nobody will know how to use it, it won't be installed on any three-dollars-a-month shared host, and it won't have any libraries.

If you can't solve the "I want to use it for $3 a month" problem, your programming language is a failure compared to PHP. If you can afford more than $3 a month for hosting, then you're not using PHP anyway. Most people learn to program because they want to share something with their friends. They choose PHP because it lets them do that, and they don't have the experience to know that They Are Doing It Wrong. By the time you introduce a PHP "reboot", you're not going to get that "Don't Know That I'm Doing It Wrong" crowd anymore, and then who's your audience?

Writing a new programming language is fun, but don't expect it to replace PHP. That's going to be impossible unless your rewrite is shipped from php.net and replaces what exists now.