It would not take much in the way of circuits, actually.
Some constant combinators can hold a list of recipes, and then a circuit that goes through the list one at a time takes like 5 combinators. With a human adjusting things once in a while, that's about all you need. Even upgrading the circuits to make specific quantities wouldn't require much.
The unholy amalgamations would show up when you're trying to make specific items on demand from scratch, or other super-optimized tasks. But beating the game doesn't need that, it needs bulk amounts of everything. And there's no optimizing away how long you'll have to wait. The best you can do is get speed modules early.
And while there's room for lots of careful inventory management and edge-case handling and failure recovery, building an alarm that goes off when nothing has been crafted in 30 seconds takes one combinator and a speaker.
It's starting to look like Factorio will need a completely overhauled tutorial/onboarding process to teach players about these features. I hope that the new features will also be staggered appropriately throughout the tech tree so new players don't have to worry about all these new factory circuit settings and signals in the early game. "This is so complicated! I'm overwhelmed! This game is too much for me!". The game as it is keeps it simple- I hope it will still seem as simple with the DLC.
Saying that, I've got 1000 hours in the game and I'll enjoy diving into the deep end with all this new stuff.
Basically all the circuit stuff is optional power-user stuff: It's not at all required to beat the vanilla game and IIRC they haven't said it will be required for the DLC either.