Soooo, theorycrafting. I seem to recall them saying they were going to make 5 seasons, which seemed weirdly specific at the time, but makes sense if there's a specific storyline they want to follow. For instance:
Middle-earth: Numenor
Welcome to the Second Age. You won't be leaving it until the last episode of Season 5.
S1: The Mariner's Wife - Aldarion & Erendis (800s)
The only nearly-complete story of Numenor before its fall, this is an easy place to start your series. It's relatively contained - you can pay fleeting visits to Middle-earth with Aldarion, but mostly remain in Numenor - and lets you pull a lot of the political side of things. If you play it right, you can also start building in future conflicts by introducing Gil-Galad and company.
S2: Forging the Rings/Tal-Elmar (1500s)
AKA The Annatar Season. Runs from his first appearance to the forging of the One, slowly building the threat of Mordor (you can definitely turn the first use of that name, and the name Sauron, into a key moment). Alongside this, we have the settling of Middle-earth by Numenor, including a narrative inspired by Tolkien's aborted tale of a Middle-earth native meeting the Kings from Over the Sea.
S3: The War of the Elves & Sauron/The Shadow over Numenor (1600s)
Interleaving the war - including the founding of Imladris - with the first touch of the Shadow on Numenor. The Numenoreans become crueler, and though ultimately they drive out the Darker advisors and sail to the aid of Middle-earth, the stage is set for later stories. Late in the season, three of the Numenorean exiles are gifted Rings by Sauron...
S4: Akallabeth (3200s)
A big time jump, which takes us to the tail end of Tar-Palantir's reign. This season runs at breakneck speed, covering Pharazon's takeover, his conquest of Sauron, Sauron's conversion of Numenor, the assault on Valinor, and the escape of Elendil & co. It's a fun one, and it ends with the Downfall.
S5: The Last Alliance (3400s)
How do you follow that? All-out war, obviously. Spend a couple of episodes building Arnor and Gondor, then witness Sauron's return and forge the Last Alliance. The war takes twelve years in canon, so there's room for plenty of material. Let me put it like this: Sauron announced his return by razing Minas Ithil and laying a three-year siege of Gondor, which was only broken when the Elves finally arrived. There's a lot to play with.
And yes, you get to end by entering the Third Age, showing Isildur's claiming of the One Ring, and basically meeting the prologue of the films. That leaves the door wide open for several follow-up seasons, including the Fall of Arnor & Gondor, the founding of Rohan, and, yes, potentially Young Aragorn as season 8.
hS
