Why do you think a sub is more likely than a center speaker in the dash? Aside from the obvious uses for music, a center dash speaker can be used for responding to the driver's voice commands and telephone calls.
I'm not sure I agree or disagree with you. Just want to know why you think that.
My reasoning is that it appears there's already a lot of speakers near the driver (door, A pillar, roof) so I don't see the justification for a centre speaker. A pillar speakers probably already make for a great phone call/voice command experience.
Sub on the other hand would boost the bass, which most buyers confuse for good quality. Personally I wish the whole "more bass = better" thing would die, but it is what it is in the consumer market. Boomy bass will sell more premium packages. (I personally have a stereo no sub system at home and think it's perfect, even $1k high quality stereo speakers they have plenty of bass for an accurate reproduction).