Sure the S8 is aimed at 'the young generation' (whatever that is). That is the reason for it being a BeoPlay product, which will be sold through the new BeoPlay channels.
But it might be interesting to the 'common B&O user' as well - or at least to those, who are willing to have a fresh look at their setup.
As I already wrote above, it might be used as a subwoofer for a 'normal' B&O/BV 5.1/7.1 setup - just let the satellites away! You could call that a budget solution, but certainly not a bad one.
When I look at the connections of the S8, I can imagine, that it could be used for the Avant as well - for those who don't want/want to invest in a big setup.
The Avant has a center and the front channels built in as well. You would only need a subwoofer and a set of rear speakers to make a slim 5.1 setup!
Connecting the sub to the Avant should not be the problem.
As I see it you have 2 separate PL connections for sub and satellites.
If you configure the satellites as rear speakers in the setup menu (of the Avant), it must be possible to use these as rears.
Have a look at the drawing - am I right?
MM