Yes, there have been a lot of under-the-hood improvements that might not be so obvious to the user but they should make it possible for more noticeable feature upgrades in subsequent versions. There have been major improvements in LayOut, too.
As for when SU2015 will come, it's anyone's guess but based on SU2014, it would be reasonable to expect the next version to come in the first quarter of 2015 or so.