Given that avast 5.0 is only 7-8 months old and I have been using avast for over six and a half years and when I started it was avast 4.x. So it will be quite some time before avast 6 comes about on those figures. When avast has a 0.1 program increment it is a bit of a big deal and many other AVs would call that a 1.0 increase (a new product).
avast is unlike other AV companies releasing a new (bells and whistles and a few tweaks) every year to get people to upgrade or new customers to buy the new version.
If you buy a 2 year avast license that is good for all program updates during that period