I come to bury Sidekick, not to praise him. Less than 24 hours after Microsoft killed Kin dead, T-Mobile has abandoned the granddaddy of messaging phones. Sidekick sales will cease tomorrow, July 2nd, and honestly? No one will care.
The Sidekick LX and Sidekick 2008 will no longer be supported by T-Mobile after tomorrow, while they "work on the next chapter" of the franchise:

As T-Mobile looks to further innovate and raise the bar for the next iteration of the T-Mobile Sidekick, as of July 2, the Sidekick LX and Sidekick 2008 will no longer be available through T-Mobile, including retail stores, care, telesales and online. While we work on the next chapter of our storied Sidekick franchise, T-Mobile will continue to provide our loyal Sidekick customers with product service and support. Stay tuned for exciting updates in the months ahead, which we expect will provide customers with a new and fresh experience.

gizmodo.com