The cancellation of 'Stargate Atlantis' in 2008 has been attributed to several factors, primarily financial issues that arose from the 2008 U.S. economic crisis. According to an article from SlashFilm by Danielle Ryan [59fb33f4], the economic downturn weakened the U.S. dollar, which in turn increased production costs for the series. Executive producer Joseph Mallozzi noted that after the show completed 100 episodes, the rising costs and the dollar's decline made it increasingly unlikely for the series to continue.
Additionally, the cancellation of 'Stargate SG-1' in 2007 after its tenth season had already set a concerning precedent for the franchise. The anticipated wrap-up movie for 'Atlantis' never came to fruition, and attempts by actor Joe Flanigan to acquire the rights for a film were thwarted by MGM's bankruptcy. This left the franchise's future in limbo, especially after 'Stargate Universe' also failed to resonate with fans and was canceled after just two seasons [59fb33f4].
The overall impact of the economic crisis on the entertainment industry during that period cannot be understated, as many shows faced similar fates due to budget constraints and shifting viewer habits. The uncertainty surrounding the 'Stargate' franchise continues to linger, with fans left wondering if there will ever be a revival or continuation of the beloved series [59fb33f4].