The original Fallon would never have started a catfight getting physical like this one does in the trailer. Fallon, like her mother Alexis, believed that their superior pedigree and education were enough to demolish people with wit. That's what trash like that little tramp Sammy Jo and her ex-stenographer aunt would pull.
And yet, the original Fallon (ie, the one played by PSM) lost *all* of her verbal wars with Sammy Jo. That is, until their last exchange in Season 4... but even then, Sammy Jo felt oddly amateur at trying to insult Fallon's hotel. It was like the writers had to dumb down SJ's own wit so that Fallon could finally have the upper hand for a change.
And, as I recall, the original Fallon *did* get physical. In the pilot, she dunked Michael Cullhane's head under the bath-water and held him there, and I believe there were at least two other times in the first season where she slapped someone (I could be wrong; I do recall one scene where she tried to slap Andrew Laird, but he caught her arm; I vaguely recall her having another slapping scene from that season, but again, I could be wrong). And she slapped Adam once, and tried to do it a second time but again her arm was caught.
Hm, I wonder if I should bring up what happened when Jeff tried to strangle her, and how Fallon just wept and whimpered and squealed and weakly tried to free herself... when it was originally planned for her to defend herself by throwing a lamp at Jeff, and that the two get into such a brawl that the room is in quite a state when they're finished.
As for Alexis, it was she who threw the first slap in her very first catfight with Krystle. Sure, go ahead and make the argument that Krystle grabbed her arm, but that's still no excuse to slap someone - especially if that someone is the parent of the baby you killed. ^^