The biggest "if". If Manafort flipped on Trump and he knew Trump knew about the Don Jr., Russian meeting conspiracy, that would make two unrelated people who corroborated that Trump knew about the meeting, Cohen and Manafort. In fact, if Trump Jr. put dad on speakerphone, then that's a huge problem. We know Trump uses a blocked phone. We know Trump Jr. called someone using a blocked phone multiple times. If Mueller was able to get a hold of those phone records and the times matched up, along with twin testimonies, they would have real concrete, indisputable evidence. No one believes Trump Jr. wanted a meeting to help Russian Children. Hell, Republicans say fuk you to American children, no way any Republican would want to help Russian children. And, if Trump knew that Manafort was changing the the GOP party platform to be more favorable to Russia, which Manafort did, on orders from Moscow, that would be conspiracy and point to multiple members of the Trump campaign being complicit and traitors. Now we know that Republicans aren't traitors and want to get to the truth. OK, just kidding. That was pure sarcasm.