Yeah, this season's been a bit rough on Sivir. We're going to be testing some changes to her shortly and are planning on helping out subsequent W bounces. Current thinking is towards allowing W bounces to crit, since that goes well with the AD itemization that's otherwise appealing to Sivir. On hit effects would certainly be cool, but adds a lot of power in some cases and would require Sivir be balanced around the most optimal cases.
As far as Sivir's strategic niche goes the ult's always been a big part of that. Strong wave clear and reasonable team fight AOE are also intended strengths though, so this change supports that well. She's meant to be weak as a duelest too, so W bounce buffs as you've identified are potentially a really good fit.
Ok it's been two weeks since Dynamic Queue has been released, what's the hold up with Solo Queue?
Tinfoil hats aside, they've stated that their highest priority right now is making sure new champ select is stable. I'd imagine solo queue isn't too far off.
The initial launch of new Champ Select and Dynamic Queues was pretty shaky, and the team's been working around the clock to maintain stability and improve the experience. You can see a list of the upcoming improvements to the system here: