I agree that the room is important, but equally, one can exaggerate the challenge. In my experience it is perfectly possible to get very good sound in a normal domestic environment. To think about the issue, it helps to distinguish more clearly between the challenges above and below the Schroeder frequency (probably about 100-150 Hz in this room). Below the Schroeder frequency, the room is the dominant factor, with often really big peaks and dips of +/- 10 dB or more. That makes for a boomy and inaccurate bass. There are three tactics for addressing this problem: bass traps, multiple subwoofers, and dsp room equalization. Bass traps are large and ugly, and are clearly not part of the OP's audio dream. The good news is that the combination of multiple subwoofers and good dsp equalization is perfectly capable of really good bass. That is important because clean, deep and powerful bass is crucial for the sense of realism that the OP is looking for. Four medium size or larger subwoofers equalized by Multi Sub Optimizer will do the job as well as is possible in a domestic environment. See here for Earl Geddes on the subject:
He also argues - and I could not agree more from my own experience - that a large room is important, and that adjacent and connected spaces can be counted as part of the listening space. At the same time, reproducing deep bass in such a large space demands pretty big power, but that is what subs are for.
The best results are usually obtained with four subwoofers, although three is often just as good and two is still pretty good. But in an ambitious system such as we are discussing, nothing beats four subs. When combined with dsp room eq they should be able to give a smooth response over a wide listening area. The most effective dsp software for equalizing such multiple subwoofers over a large listening space is probably Multi Sub Optimizer. It can even be used to optimize the low frequency response of the main speakers. However, I would probably prefer to high pass the main speakers, i.e. not let them play much below the crossover frequency with the subwoofers, of, say, 80 Hz. This keeps the main speakers in their comfort zone, for lower distortion and a bit more headroom. In that case, you probably still need a bit of filtering in the range 80-250 Hz. This could be done by MSO as well, by e.g. Dirac, or by a combination of manual measurement with REW and some filters on e.g. the RME ADI-2 DAC/preamp. The latter is what I did.
Most experts agree that trying to use dsp eq above, say, 250 Hz is not a good idea. Peaks and dips are extremely narrow the higher the frequency, and moving your head even a little bit changes their frequency. The problem here is reflections. The only way to deal with them is some damping. Serious treating of rooms for this problem has to be designed by professionals, and may not look pretty. The practical version is to have some soft furnishings like curtains, book cases, a nice Persian rug etc. Sonically, the problem often expresses itself as a harsh sound, so speakers with an elevated top end should be avoided. In addition, traditional tone controls or modern versions of that can be very useful. This is one of the reasons why I like my RME ADI-2 DAC so much, because it has precisely such tone controls (plus a lot more).
In short, the biggest problem with rooms is in the bass, and for that we have effective and good looking solutions. Above the Schroeder frequency it is esthetically a bit harder, but even a somewhat compromised solution can still sound very good. My Quad electrostats sound great in a relatively minimalist interior with a fair amount of glass, and without any ugly damping panels.