Yeah I said this in another thread: that unless a star player is trying to force his way to a team that doesn't have the space to sign him, a star, max level player has zero incentive to agree to a sign and trade. Why would someone who has destination options where he wants to play, that has cap space do a sign and trade to go to a less desirable location that helps his previous team and takes assets off his new team, when he can just sign outright where he wants.
Though not "literally" impossible, they are logically impossible to pull off with a star player unless that star player's primary desire is to play for a team that doesn't have cap space.
Kyrie has 2 options in LA, 2 options in NY, one in Dallas and one with Indy. All excellent options and a few that make the most sense for Kyrie(LAL, Brooklyn and NYK).