As mentioned in my earlier response, I just think she looks really hot and that was pretty much about it. I guess I do like that Sinon is in a position of enjoying whatever she's doing, cause she was more or less being abused by Hebishima. But in terms of chances of success, I'm still waiting to see how the story as a whole develops to conclude where everyone is going. Like at the current moment it does seem like Fujino wants to also turn Kirito into a manwhore or a dude being consoled by Suguha and Sinon, but it could all just be a set up to make Kirito lose access to all those girls around him.
As a side note, it does seem like the "cheating buff" Kirito gets seems to also apply IRL? I feel like some people probably pointed this out from previous updates, but I'm mainly just referring to how Suguha mentions Kirito seems bigger than normal. Which by the way it's funny that Kirito doesn't really recognize or question why Suguha is mentioning that. Probably a reference to how it's bigger than when they were kids or something I guess? But either way, I assumed Suguha was talking about how it's bigger versus her other escapades with Kirito.
Going back to Sinon, I don't think she'll have any major sex scene with anyone until like May at the earliest though, so it's just a longer painful ish wait. And when I say major scene, it's probably like a dedicated moment for her whenever she decides to bang Kirito, or gets screwed over by Shadow Fox.
Edit:
Also for those who probably didn't check, but if you resist Sinon, she doesn't give a titjob and gives a handjob instead. The titjob was really hot though.