Concerning the Marg-Robert plot, 2 things: 1 Could Tyrion end up Lord of Casterly Rock in that scenario, either Tywin forced to publicly accept and name him heir as an enforced humiliation, or Tywin fighting & dying for his golden twins, or is Tyrion too closely related to escape being tarred with his siblings’ brush unless he turned on them which he’d never do absent Tysha-truths coming out?

Marg-Robert ask 2 Doesn’t it seem like there’s a whole lot of potential trouble if it succeeds? The Florents resent the Tyrells, and now Marg gets a crown where Delena got shame, her son gets to be heir while Edric is a Storm & alienated from his mom. And Stannis is their good-kin. Is that the safeguard against any Florent reaction or does he get brought into a Florent-Tyrell war dividing the Baratheons? If Robert dies, a regency for Marg’s son HAS to turn bloody right?

1. Interesting. I think it’s possible, but I’d lean more toward a different branch of the Lannisters being given the pre-eminence. 

2. Given their actions in OTL, I think the Tyrells generally consider a crown to be worth the trouble. But as I’ve discussed before, GRRM made a bit of a mistake in making the Florents too small to really fulfill their role as a threat to the Tyrells of Highgarden.