Robot Spirits to the Mobile Suit In Action! and In Action! Offshoot lines.
Super Robot Chogokin to Soul of Chogokin to regular Chogokin, despite both regular and Soul versions still exist.
Hero Factory temporarily substituted BIONICLE (it even said so on the packaging of the first-wave figures). BIONICLE itself was this to the earlier and short-lived Slizers and Robo Riders lines. Note that fans on the other hand consider Ninjago to be its sequel, story-wise. The earlier BIONICLE Rahi models were successors of the LEGO Competition playsets.
After ToyBiz lost the Marvel Comics license to Hasbro, they attempted to continue their popular Marvel Legends series with a new line called Legendary Comic Book Heroes. The articulation, sculpting style, paint work and even the Build-A-Figure concept were all carried over from Marvel Legends, only now applied to non-Marvel characters like Judge Dredd, Witchblade, Savage Dragon and Madman. Unfortunately, the line failed to recapture the success of its predecessor, and ToyBiz ended up going out of business.
The Barbie Look and the Tim Gunn Barbie dolls can count as this for the Barbie Basics line, both being collector, easy to find, fashion focused doll lines with the model muse body -more realistic and skinny- As the Basics were were officially discontinued few months before the Gunn dolls were announced. And Word of God stated The Barbie Look was created with this intention.
Nintendo's amiibo toyline is a spiritual successor to Nintendo's ill-fated e-reader accessory for the Game Boy Advance (even more so with the amiibo cards), and because Technology Marches On, they work a lot better than the e-reader ever did.
Eight years after the end of M.A.S.K., Kenner (now under Hasbro ownership) created Vor Tech Undercover Conversion Squad, another cartoon-backed toyline about two rival team of agents fighting with superpower-granting helmets and transforming vehicles. All but one of the Vor-Tech vehicles were retools of MASK toys, and according to one of the writers involved in the Vor Tech cartoon, the brand created by Hasbro as a way to reuse the M.A.S.K molds (apparently as the then-recent Jim Carrey movie made using the M.A.S.K name not viable).
GoGo's Crazy Bones has a spiritual successor in Star Monsters. Both series are made by the company Magic Box International, both series consist of plastic collectible characters, both series have characters with alternate paint jobs (Gogo's has the Wanted and Most Wanted characters, Star Monsters has evolutions of existing Star Monsters), both series have games associated with them... the list goes on, doesn't it?