I know it might sound crazy, Adherennium Dr of Phoolishness , but try meshing all those plot bunnies... yeah, I know that a literary Frankenstein monster might come out of it... but maybe it cuts the knot.

And what about your worry of rewriting certain other existing works... you're not copying but holding on to a buoy in the sea of plotlessness. You can use an existing work (Steppenwolf) as a start to your What If... only for the exercise, though. (Otherwise it's really stealing.)

I, for example, have two parallel stories this year - a romance part & a crime investigation - and didn't know how to write my What Ifs at first. As you can see by the plural, I wrote two separate ones, focusing on either part... but it read off. It wasn't realistic to separate both story lines as they hugely interfere with each other.

After I interwove them for the exercise, it reads more coherent and like something to base a Prep on.

Even more this exercise doesn't have to be set in stone... as the Prep evolves, also your plot will come out of the murkiness and evolve along with the following exercises... and finally reveal itself.

Therefore you could also continue with one of the other exercises. A flash of an idea that fits with day 23 or 7? Go for it! It'll definitely influence your What Ifs... and you can work on it by going back and forth between inspiring exercises and puzzle their outcomes into first your outlines and so eventually your What If.

Retrocausation is an interesting concept, isn't it?

You will do it eventually, young man, you know that, eh?