Hi!
X-Cart 5 will be LiteCommerce 3 plus a few paid modules for LiteCommerce 3 plus commercial services. So, technically LiteCommerce 3 is X-Cart 5.
One of the paid LC3 features which may be included into X-Cart is eGoods (digitally distributed products). eGoods will require the free "File Attachments" module to be installed in the shop (eGoods will use its code and UI). Any we need your feedback on the "File Attachments" module
before we start coding it! See
http://forum.x-cart.com/showthread.php?t=60304
Thanks!