I agree that there is too much in the way coming for TWD spinoffs. It feels like they're over-saturating the market, as Star Trek and Star Wars are currently close to doing. Do we really need 2 spinoffs at once, plus the Rick/Michonne mini-series? And Fear is still limping along.
I'd love to see them focus on one thing at a time. I'm all for planting seeds to pay off later (I love that) but planning something this big, which could never come to fruition in this series feels like a bit much.
I guess I should revise that... in the comics, the alst book was a decade or so after the events in the Commonwealth. Maybe the last episode of the television show will also be 10 years later and have the smart walkers in it? But even so, that wouldn't be very fulfilling. And it negates everything they ever did, stabbing people in the head to prevent them from turning, killing walkers, etc., if they could potentially 'come back'. That's what Herschel had been trying to do in his barn way back when.