CodeIgniter on PHP 5+ only?

[eluser]whizzer[/eluser]
Hello,
me and my colleagues are in the process of rewriting a large website with 1M+ unique visitors a month. We're making an update because the website is growing very fast and we need more people to write code and a framework is the perfect solution. We've had some small projects with CI before. However in this case we're seeking speed so we decided to use a really fast framework. I know this is a plus but with its compatibility with PHP 4.3+ CI is a bit slowed down. So I'm wondering if there will ever be a PHP 5+ only version, using the full potential of the object-orientated model in PHP?
Thank you.