That really is a problem these days as more TVs are using some very low profile stands for free standing. There may be some soundbars that putting the TV on top of one would be doable, but I have to admit I haven’t found one. What might be more doable would be a furniture design with a TV on a higher level shelf with a lower shelf for the soundbar.Given the popularity of sound bars, I'm rather surprised that more of them aren't set up to have the TV sit atop them. You can't bury the IR receiver behind the screen anymore and so many of them seem to be blocked by even a modest sound bar.
I’m seeing more people wall mount their TVs, especially the ones 65” or bigger as the mounts for free standing are not all that good, or very big themselves. With a wall mount there are some after market things to mount a soundbar as well, especially for the smaller soundbars.
Making a soundbar big enough for some of these TV free standing mounts could be done but I wonder if there is enough of a market?