Due to sliding sales at all automakers for conventional body-on-frame, 4x4 station wagons like the Chevy Trailblazer, Ford Explorer, et al., GM is rumored to have decided to let the current Trailblazer, GMC Envoy, and all the other Buick, Saab, and Isuzu derivatives sell in their current form until 2010 (or whenever it makes sense to stop selling them - like the Rainier which will leave Buick at the end of the 2007 model year) when a new cross-over would be introduced.
This, as yet unannounced crossover would be smaller than the recently announced Saturn Outlook, Buick Enclave, and GMC Acadia which are all essentially full-sized crossovers with the same room as the body-on-frame Tahoe, Yukon, and Escalade.
A new mid-sized crossover would need to slot between the Tahoe and the smaller Equinox. Though the current super-sized compact SUV niche occupied by the Equinox could make this difficult. Perhaps we'll see a version of the, smaller, Chevy Captiva from Europe as the next Equinox to make room in the line for a true mid-sized crossover.
See one of the many reports of the Trailblazer's demise over at the Detroit News:
Detroit News - Chevy may junk Trailblazer...