Tosh's doll works on Tychus, meaning it's possible to psionically mistake Tychus for Raynor.
In the secret mission, you can see a monitor showing people stealing a couch.
There's actually no evidence at all, in the Protoss missions, that Kerrigan is going to save everything.
Aside from you know the mission where Zeratul talks to Tassadar and Tassadar tells him the Overmind created Kerrigan, so that the Swarm could break free from the Hybrid's rule and then in the next mission you see what happens if the Hybrid control the Swarm.
So . . . what? First, you're trusting some weird glowy guy who's been spending his time near the Overmind's corpse. Secondly, what does the Hybrids controlling the Swarm have to do with Kerrigan saving everything? There's an implied connection. There's no evidence
Then the Hybrid even tells the Protoss in the last of the Protoss missions that there was one who could have saved them but they killed her and the Protoss unanimously say 'Kerrigan!'
But you're right, no evidence what-so-ever. None.
Reading comprehension is in short supply these days. The Dark Voice says that there was one that might have stopped him, but in their recklessness, the Protoss mistook her for the true threat.
No names are mentioned in that statement.
We already know Zeratul's opinion. But the one everybody jumps on is Artanis' "Kerrigan? How could we have known?"
All that means is that the Protoss were fooled regarding Kerrigan. That could just as easily mean being tricked into keeping her alive as them killing her. There are already any number of female characters in WoL Liberty who could fulfill the requirements of both being "her" and being "mistaken for the true threat."
Given the trailer's I've seen, Nova could easily top that list, since she's out to get Kerrigan, the presumed savior of the universe.