Yes, the real limit is actually lower than 22 kHz and it becomes lower while you age. I don't know how they justify the 192 kHz sampling rate. Actually, most audio CDs are mastered so badly that the quality stays far below the possible. Usually, tracks are recorded too loud so that they still sound "good" (whatever that is) on a pocket player. Thus, you lose a lot of dynamic on a CD due the 16-bit resolution. The 24-bit sample resolution might therefore improve things but they could as well master the CDs properly and this little improvement hardly makes up for all the disadvantages.

I could even imagine, that they would purposely decrease the record quality of CDs in order to convince people of the "superior" audio quality of DVD-Audio.

How do you want to record tracks from a DVD-Audio to your pocket player or car player? You'd either have to buy special hardware or record analog (now comes the bummer) in realtime! I have a Minidisc recorder/player and this was the main reason I recorded very few discs. It's just too much hassle and time.