I have family that flies private and for them this would probably be cheaper and more comfortable than that (although then you have to deal with the time/airport hassles of commercial).
Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime. Mark Twain
Etihad says prayer areas ... are equipped with a real-time electronic Qibla-finder showing the exact direction of Mecca based on the aircraft's geographical position.
I'm actually surprised it only costs $20K each way. It seems to me like they could make more money than that by putting in coach seating. I'm hard pressed to believe you couldn't get 20 coach seats into 125 square feet, the way they pack them in there. I also would expect that coach seats sell easier than these residences - when H and I flew to/from Dubai in first class, they had 8 seats but there were always a few empty seats and H and I weren't revenue generating seats, so it doesn't seem like this "residence" thing would be that great for revenue unless they know they can sell it every flight.
On a route like London - Abu Dhabi I would imagine they will have no issue selling out, the amount of wealth in the UK from the UAE is staggering.