Awkward wan k a!
I read a few reviews on this soundbar. Apparently it does a decent job on its own, however, many people will miss not having the bass module which is ~£300 more. On top of that you can add a couple of satellites for an extra £300 on top of it. Needless to say Bose is only compatible with Bose, so if buying this thinking about expansion in the future, bear in mind that this will be quite the investment.
This or samsung Q70R? Any idea!
All you need is an HDMI switch that supports digital optical out. I don't have a wall mounted TV but have 4 different HDMI devices going into 1 HMDI socket on the TV via a remote controlled switch. You have the other devices, and the switch, off wall ( so to speak ) and then just run 1 HDMI and 1 digital optical cable through the conduit. This does, of course, assume your sound bar has digital optical in. If it doesn't then it probably isn't very good ;)
Or get another amp/change tv to one with a One Connect Box as I have one 25mm conduit in the wall see above. But the One Connect Box cable end seems too big to fit down conduit.