I worry that within a matter of years it will become practically impossible to replace the stock head unit in mainstream cars.

What gives me comfort in this instance is the following bits of information...

1. Mainstream cars will start having empeg-type stuff built in, some of it even being designed and coded by the Cambridge team. Case in point: Camelot, etc.

2. CD changers are still popular, so the little CD-changer-becomes-aux-input boxes will still be available for the foreseeable future. And at that point, you can plug a Karma in.

The latter is what I'm currently doing in my wife's car. I bought one of those little CD-changer-becomes-aux-input converter boxes and there is now a tiny 1/8" jack in her dash on the inside of her knicknack pocket. Works perfectly, Karma plugs right in and sounds fine.