It really depends on what modders want to do with the character as they are only limited by their ability and their imagination. If Vash was recast, who's to say that she'd even want to go Dantooine? It might even be a modder's favor for her not to want to go to Dantooine as the other Jedi Masters do not acknowledge her being there at any point in the Rebuilt Jedi Academy discussion. Let's look at few things that could be done - and folks could add items below as they occur to them.
Continue the discussion on Force Bonds that currently exists in the game disc files? Would knowing more about the Force Bonds be of interest to a player?
Have lengthier discussions with Vash on the nature of their player's current alignment?
Perhaps Vash might offer an apology (on her own behalf that is, not the Council's) for throwing the Exile out of the Order?
Expanded training montage?
Could Vash have additional feedback on the Masters that the Exile has encountered already? Additional comments branching off of whether your Exile spared them or attacked them?
How about some more information on what she did on the planet? She has to have more information on the nature of planet of M4-78. Assuming we're talking about a version of a mod that includes Kaah, then she was standing right next to her hacker padawan having things explained to her. Her (relatively) calm outlook compared to Kaah's might offer different outlooks on M4-78 as a whole.
And perhaps the player could suggest to Vash what she could do next? Maybe tie Vash into other mods that aren't connected to M4-78 right now (i.e. Korriban Expansion, Vash being a resource to consult about those pesky missing Jedi Holocrons, having her pick up and train Kaevee, etc.)?
And that's just off the top of my head.