Whilst I'd love to see Codeigniter working with the latest PHP version ( I'm currently running it on both dev and production using PHP 5.6) we have to be realist about the hosting availability. A lot of sites are going to be hosted on shared web hosting, which in most cases means Centos/cPanels.
So perhaps rather than setting our PHP version why don't we just peg it with cPanels with backward compatibility -1. Codeigniter has always been good with backward compatibility and I would hate to see us lose that.
Most things broken in our house was done by nobody, the rest was my fault anyway