I don't think they will abandon AirTunes. This is a huge selling point for their more "consumer" based routers. The AirPort Extreme is the more professional version, kind of like the MacBook Pro's, Mac Pro's, etc.
On the "Pro" version, they give you AirDisk and Printing, everything a pro users needs, music is just an added bonus you need to buy. To add the AirTunes functionality, you need to buy a separate AirPort Express..(More money for Apple).
It is either because they want to make more money so you buy both, or they want to have 2 products directed toward different people, or a combination of both. Plus you can still print with the AirPort Express and most average computer users don't need an AirDisk. Most don't even back up their files on to an external.
I think Apple has it figured out. They wouldn't drop that product unless they came out with a new one with the same features and more.
As for Front Row, I felt it was an added goody FrontRow 1.0 played using iTunes so you could just change the speakers to AirTunes. But ultimately they wanted FrontRow to be it's own application, independent of other applications. In doing so we lost a valuable feature. Hopefully they will notice this and add it into an update.
It would be ridiculous to make everyone buy AppleTV. I don't even have component inputs on my TV so I need AirPort for my music.
Only time will truly tell though.
ND