Gibson has made some interesting decisions over the years. Here is some history from a drummer's viewpoint.
I love Slingerland drums, I always have. Gene Krupa and Buddy Rich were Slingerland artists back in the day. Neil Peart played Slingerlands early in Rush's career, although he was never an endorser. They made amazing drums in the 50s and sixties, personally I find their drums from the mid sixties in particular to be spectacular. In the seventies they lost a little sheen, but still made very high quality drums. In the late 70s Pearl, Tama and Yamaha all made big inroads and knocked all of the American drum manufacturers on their butts. The Asian brands made innovative products at prices that the American brands couldn't compete with. Rogers didn't survive, Ludwig and Gretsch barely made it through that period. Slingerland went through a series of owners, eventually becoming a Gibson Brand.
In the late 80s, early 90s DW came up with a business model that worked. They were making custom drums in America, charging custom prices and marketing them as a premium product. they went from being a small company to being THE big dog of American drum companies.
Gibson made a go of it. They moved production to Nashville and build some great drums. Unfortunately , the Slingerland name didn't resonate with buyers who remembered the crappy drums that they sold in the 80s, certainly not at DW prices. Gibson's marketing of these great drums was pretty weak as well. The brand had lost it's lustre in the eyes of many, sort of like Cadillac. They moved production to Conrad Arkansas for a few years and eventually gave up on the drum business and closed up shop. This was around early 2008.
I had bought one their amazing "Nashville era" Slingerland Radio King snares and was saving up to order a full Slingerland kit. Alas, when I was ready to put the money down I found out that production stopped. In July of 2008 I bought a DW Collector's Series kit for the same money that I would have spent on Slingerland.
Since then several American companies have tried to buy the name. Gibson refuses to sell it. A company called "The Chicago Drum Company" has some of the old tooling and Niles Illinois employees. They make some great drums that are pretty much reproductions of the revered 50s and 60s Slingerlands. (Very similar to what "Heritage" does in making models similar to Gibson in the old Kalamazoo plant.) DW builds a line of drums called the "Classic Series". They don't look like Slingerlands, but they sure sound like them. The shells are built to 1950s Slingerland specs. Maxwell drums also make a line of Slingerland clones that are wonderful. Steve Maxwell tried to buy the name from Gibson and was told that it wasn't for sale.
Unfortunately, the longer the Slingerland name stays out of production, the less it means to current drum buyers. It is a sad state of affairs.