Great. This should have happened about 2 years ago.
I have about 50% of stock XC 4.6.5 js code removed on my site and replaced with pure HTML5/CSS3 functionality.
Get the bugs fixed. Get all templates rewritten to better and proper html and css. Get the js code at the end as much as possible. I wouldn't even mind if XC 4.8 ships with just one skin as long as this skin is done right. Why not base it on one of the responsive frameworks available and go from there.
It wouldn't be a bad idea also to have the scripts PHP 7 ready as much as possible. It is coming and it is very promising especially in terms of speed.
http://php.net/archive/2015.php