My comments:
on point 1: there is nothing more to add here that
LSC82 has already said
on point 2: outside my interest
on point 3: this multipath already has the end flag, what it will look like remains to be seen
on point 4: this multipath already has the precursor to the end flag, what it will look like remains to be seen
on point 5: there is only one question here: is John Erynn's father? If so, the conversation between Melissa and Emily will be very interesting (or not). But I assume that Melissa will (again) get involved with John and Emily will return to her real love, Santi.
I'll throw some thoughts about the ones i didn't before(because why the fuck not right

).
Nikki-Cara,
MilesEdgeworth said "Nikki/Cara vs Alexis", but to me Nikki/Cara don't feel aimed at any particular girl we can develop a relationship, anything that can be said about them vs Alexis, also applies to Erynn, Layla, Val... nothing ties them to Alexis in particular.
So in a way they are quite a generic "lover from a different town coming to cause havoc with your current boo".
Also goes without saying that they are always discussed as Nikki/Cara and not Nikki and Cara, despite having different personalities the plot points are always the same for both sisters... which makes it feel even more generic.
Val does have specific behaviour tied to Alexis, so far Alexis is the only LI that causes her to behave differently, if she's in a combo with Erynn or Nikki, she's totally unaware.
It will probably end soon however, we already had the option to break up with either girl for the other... i can't see the YOLO choice where you keep messing around with both girls going much further.
The MC even thinks to himself how screwed he is once Layla catches wind of the fact he's dating Val.
He told Val he would break up with Alexis and Alexis of course won't appreciate him being a cheat.
It's a combo that burned bright but will die fast.
And yeah the Melissa-Emily conversation will be hillarious to watch from a distance... and John-Emily certainly won't have a long future since an eventual marriage would block the Erynn(and Iris) path.
The MC moves out of Riverside and splits from Nikki/Cara to protect the Andres-Haley relationship, i think this time John and Emily will be the ones to take a step back for the happyness of their children.