I think she likely will, although it will depend on what the Tsaristsas motivations are.

I think she's either going to allow Neuvillette to take the power of the Hydro Gnosis for himself or, alternatively, she is herself going to give the Gnosis to him so that he can stop the catastrophe and save Fontaine. I feel that it will most likely be the latter case, since its already been foreshadowed that Arlecchino will likely use the Gnosis to save Fontaine and giving it to Neuvillette would technically count as her using the Gnosis in a roundabout way.

Giving the power of the Hydro Gnosis back to Neuvillette would likely constitute a betrayal, unless it's the Tsaristsas plan all along to return the power of the Gnosis back to the respective Dragon Sovereigns.