Before owning my Bose Companion 5 PC speakers, I didn't believe you could get good surround sound from speakers only in front of you. The Companion 5 offers 7.1 surround in a two-speaker and subwoofer physical configuration.
These soundbars use a lot of advanced sound tech like this to make you think sounds are coming from all directions and you don't have to run speaker wires through your walls.
Of course the receiver market is "not declining as much as might be expected."!
I have my Yamaha AV amp connected to a pair of Q-Acoustics Q2050i speakers and a Tannoy subwoofer. A soundbar simply cannot create a genuine (as recorded) soundstage and smooth frequency response of a properly positioned stereo speaker setup. What's more, you're not going to get anyone with an interest in music using a soundbar to play their music - proper stereo speakers and a potent AV amp (that serve for both audio and TV use) provides the best possible solution.
Soundbars remain a necessarily compact solution for flat TV's that can never accommodate the correctly sized cavities for proper loudspeaker sound reproduction, and/or for rooms that cannot accommodate proper loudspeakers.
Location location location! I don't believe it one little bit. You can trick the brain but you can not change the way set sound devices deploy to the ear. Will be very well received if they somehow can tho. Dam them pesky wires!!
Sorry Tom's Guide - but your assertion that this or any soundbar poses any risk to the AVR market is severely off the mark. There is no soundbar - up to and including the Sony and beyond - that will EVER compete with even a mediocre AVR and component system.