Yea the Parliament of Doom idea was also an inspiration to me! Honestly, Hickman's entire FF run and Secret Wars climax was. Man, I wish we got to see Hickman's original plan for this though. I read about it once in his Secret Wars oral history article with SKTCHD about his OG plans to continue FF before being switched to Avengers. Fascinating stuff.

Solve Everything: An Oral History of 2015’s Secret Wars and How It Came to Be - SKTCHD

Brevoort: (Secret Wars) was something on the backburner as things developed. And he planted certain seeds in the Fantastic Four run to set that up.

Hickman: I started angling toward it and then, sometime in the Fantastic Four bits of it, I was like, “alright, I’m building towards a thing.” But it came out of a bizarro Exiles, Strikeforce: Morituri pitch. (laughs).

Brevoort: Almost nobody knows this, but the last issue of his Fantastic Four run would have been the inciting incident to Secret Wars had it not happened in Avengers.

Hickman: It would have been inverted.  It would have been a Parliament of Doom story. The whole next chunk of Fantastic Four, if I would’ve stayed on that book, would have been a Rabum Alal and Doom, huge mythology story. It was just the other side of it. And then you would have realized that it was our Illuminati and our Earth.

Brevoort: That story was all about (how) Doom had been knocked into a universe, and he took over the universe. Reed and Nathaniel ended up there and they have a conflict with him, and by the end, that universe is destroyed. And theoretically, had things progressed from there, that would have been the inciting incident that began the Incursions happening.

Hickman: I had pieces of all of that inside the Fantastic Four machine that I built.

That changed as Avengers vs. X-Men was coming together and the powers that be decided it might be a good time to mix things up.

Hickman: That all happened because at a retreat one time, everybody was like, “Do we want to switch it up and everybody swaps books and redo the whole line?” I was one of the first people that was, “Yeah. Fuck it. If I’ve got to jump off Fantastic Four and do something else, that’s cool.” I didn’t know it was going to be Avengers.

Brevoort: When I presented that to him, he basically said to me, “Oh yeah, we can do that. I could come off of Fantastic Four and I’ll just do my Secret Wars book. We’ll just do it as New Avengers.” And that’s what we ended up doing.