The list is just a list of hypothetical choices! I do intend to drive my A4 until it's worn out beyond the point it makes sense to keep. I'm surprised you remember my comment about the A4 being my last (new) car with internal combustion engine. I'm still serious about that, but right now I don't see any alternative fuel vehicle that I really like and, at least at this time, I'd rather buy a used car than a new one. Who's to say what choices we will have in 5-7 years?
As far as the Mazda 3 goes, I put it on my list, because it drives very nicely, like a small BMW, and because I like its styling and design inside and out. Cost taken into account, the Mazda 3 seems like a good value and I would not get bored quickly with it. To me it looks much nicer than its Ford Focus twin. I really can't say much about reliability, as I simply don't know, but I haven't heard anything bad about the Ford Focus in that regard.