Seliph is no longer a legitimate heir to Granvelle as the first born son is Julius. Seliph gets significantly less support from civilians and is not called the Scion of Light. In their point of view there's little hope to be had to tout such a title. Leif might get more traction in his situation or he might just be erased from history without Seliph coming in to save the day on time. It's a coin toss.
If the scenario remains the same where she wins over the Isaacians and continues as usual, endgame is where it gets politically interesting. She'd need to bear a son, that bullshit Deirdre had to go through and have a prince consort. I'm gonna throw Shannan out there since he kept her hidden and helped raised her in his kingdom. The landscape might change significantly, with Isaac and Granvelle unifying or splitting up into smaller states.
>but chalis why can't she just be an empress in a newly found progressive society
feudal jugdral is no place for an easy fix and also i like what i came up with better