I wouldn't sell Buick simply because GM needs to sell vehicles at higher price points to support the ones at lower.
It's hard to convince people to buy into a new brand - moreso luxury brand - without making either a REALLY excellent product or offering it at an exceptional pricepoint.
With Buick, I do still see the brand as somewhat upscale. Not for me at this point in my life, but something of a common --err, 'accessable' traditional luxury type brand. With better products it would be a more credible brand, and one GM could do some intelligent platform sharing with Cadillac or Saab and share the costs of engineering across more volume. That said, if GM tries to make it more hip like and firm it up, really is little point.