I thought up a loose idea for a G3 that takes place so far into the future of G1 it basically works as a reboot too. Tahu and the gang are Turaga and the story starts with six new Matoran becoming Toa (maybe the Bohrok Kal elements to spice things up a bit). Main villain (at first) is the Shadowed One, who wants to take over the Island and then the world, as is villain custom. for the first year he just sends corrupted Rahi after the Toa as they collect masks, keeping things simple and replicating 2001.

Year 2 the Toa get obligatory power-up, Shadowed One decides to use an ancient weapon against them: the mask of shadows, which once belonged to his old nemesis Makuta. At this point Makuta is a legend, essentially a horror story the Turaga tell the Matoran of in the night, and how his brother and their savior Mata-Nui (who their island is named after) defeated him. Anyway, TSO uses the mask of shadows to create shadow toa, sends those fuckers after the A-team. Through the power of collecting every new mask (only 5.00 a pack at your local toy store!) the Toa beat the shadow clones and go kick the Shadowed Ones ass, utilizing a new Exo-Toa to do it (TSO and ET are titan sets)

Year 3 is when shit gets bonkers. The story is split in two, like how 2003 was Bohrok Kal / Mask of Light. TSO, with his ass thoroughly kicked, realizes his only chance at winning is to resurrect Makuta and become his ally. To do this he must retrieve the mask of time, which is being kept on a hidden island far away by its creator, Vakama (who is the only surviving OG Turaga). TSO sends that winters canister sets, six dark hunters, to slow down the Toa while he hunts for Vakama. The Toa make it to Vakama's island shortly before TSO and the dark hunters. A battle ensues, TSO kills Vakama and jacks the Vahi, he and his goons peace out. Back at his fortress he succeeds in resurrecting Makuta and proposes becoming equals (with the intention of stabbing him in the back later). Makuta kills TSO, tells the dark hunters to serve him or die, and lays waste to the Island just as the Toa return. They find a wounded Turaga Gali (who is basically the Vakama of G3, the wisest of the wise old guys) who tells them that now there is only one other who can hope to defeat Makuta, and now they have to find him.

While the first half of the year was the quest for the mask of time, the second half is the quest for the mask of light, and is a huge callback to the OG arc. The toa go on a quest to find Takanuva, who is still a Toa and has isolated himself for edgy reluctant hero reasons. Makuta, realizing Takanuva is one of the few who can defeat him, creates six rahkshi to kill the Toa before they can find him. Along the way they find two other Toa from the years of legend: Jaller and Hahli, each with a badass mount and a pretty dope titan set. They lead them to Takanuva's temple, where they are attacked by the Rahkshi. Jaller is killed, and Takanuva in turn kills the Rahkshi (again). Takanuva finally agrees to return to toa-ing and hops on the Ussanui 2.0 (which is the biggest set of the year, comes with an updated Takanuva and a silver axalara-t9-type-thing this time around) to go fuck up Makuta. Meanwhile, the Toa form an uneasy alliance with the leader of those six dark hunters from earlier (who was the Shadowed Ones second in command), who wants revenge on Makuta and offers to sneak them into his fortress. The toa and the six rogue dark hunters tear apart the fortress fighting the rest of the dark hunters while Takanuva and Makuta duke it out (not play lacrosse) in the middle of it all. In the end the dark hunters are defeated (all except the leader of the rogue ones are killed), Makuta is beaten in a really vague, he-kind-of-just-disappeared-and-will-totally-return-later way, and Jaller is revived with the mask of time. The island is rebuilt, a funeral is held for Vakama, and at the very end Gali begins to tell a story to the toa, about her, Tahu and the gang.

Haven't thought it out much, but the next two years would be a prequel similar to 2004-2005, except this time it's two years of the old guard and the story of how they became Turaga.