Complex sentence: It would be the final studio album to feature Rick Wakeman until his return in 1991 (on the "Union" album), and the last to feature Jon Anderson until the band's 1983 reformation.
Split into simpler sentences: It would be the final studio album to feature Rick Wakeman until his return in 1991 (on the "Union" album). It is also the last studio album to feature Jon Anderson until the band's 1983 reformation.