This is the thing with Suguha, what's the next step for her?
Because currently, while she is enjoying raping and harassing Kirito, she is neither happy nor content with her current situation. She wants more than simply taking advantage of an unaware Kirito, she wants him to willingly chose to be with her.
For now, while Kirito is not rejecting her, so she is fine and enjoys the occasional session of sleeping incestual draining, but sooner or later that won't be enough for her, so she will push things further and further.
Kirito might not lose Suguha like he did Asuna, his sexual incompetence is not really a factor here. The problem for Suguha has always been that Kirito will most likely never accept her feelings for him, what changed for her since her fall and rise with Hebishima is that she is now willing to do anything to get a chance with her oni-chan.
So, if Kirito were to deny her of that chance in the future, who knows what might be the path Suguha will take, from going yandere and raping him, to going back to Hebishima willingly, or even some random NTR token character like Inoda might work for her at that point.