I beg to differ. The general public has been adequately exposed to Intel's marketing for the i3/i5/i7 processors, so much so that they have been entrenched in people's minds, consciously or otherwise. The increased proliferation of these processors in PCs have also led to increased awareness. If Apple continues to market their MacBook Pro line alongside others which have these newly-branded processors, they will certainly suffer. Every PC manufacturer with products in the same price range out there has already made the switch to these processors. Even Apple's own iMacs come with i5/i7 processors. It is not hard to see that people will tend to shun the MacBook Pro.
Certainly, there is truth in your argument. Indeed, the average Joes do not delve into technical minutiae when purchasing a computer. However, marketing on TV, billboards, the internet, etc. does such a good job the "Clarkdale" and "Arrandale" differences are blurred to them, leaving behind the consumer-friendly branding of i3, i5 and i7. Consumers generally don't care how good something really is. To them, Core 2 Duos sound like yesterday's technology, and i5 sounds like something better - even if a high-end C2D might perform a lot better than a mid-end i5 processor, consumers will generally go for the i5-powered products.
Do not underestimate the power of marketing. Impulse buys are usually directed by snap judgments which are heavily influenced by marketing spiel.