Perhaps she will be referenced in a future game. For example:
there could be another game with Soma in which someone evil tries to corrupt Soma using the Dominus glyph somehow. After all, when someone who absorbed a glyph dies, it leaves their body. It could be said that after Shanoa's death, someone took and seal the three dominus glyphs and stored them somewhere safe. However, one day they were stolen. And then, a monster with dominus attacks Soma. He kills it and when the glyph appears he recognizes it as being connected to Dracula's power. At which point, Arikado tells Soma not to go near it, that someone may be after him again, and to let him handle it. However, like in DoS, Soma doesn't listen and gets further involved.
Something like this. Also, the reason I think that the three glyphs are called Dominus is because they are suppose to be the strongest and thus they Dominate. This all just speculation.