It's true I don't see much difference in terms of the visual but I also take into account quality and reliability etc. I do see some marked differences in how each HD shows when comparing price points ( that is 600 dollar 720p vs a 900 dollar 720p) I guess because they have different refresh rates and contrast ratios.
But i don't think all of them look the same unless both has the same specs; and I don't really shop on brand name unless to ensure I getting a quality product.
It will hurt Samsung who were their previous partners. Samsung rose to the top of the LCD market because of their partnership with Sony, they might lose some branding there and people may go over to Sharp since it has Sony's backing. Sony account for 2-3 trillion won of teh 4 trillion of sales profit that they got from their LCDs.