There are many different ways our story could continue.I'll just make a suggestion.
So, here it goes:
Even now in times of "peace" (pandaria) the Sin'dorei cannot rest.A civil war errupts inside Silvermoon between the ones that want to literally and metaphorically be "purified" throught light with Halduron Brightwing as their leader and the ones that believe power is what makes them what they are and therefore power will carve the path to a better future.The second group being lead mainly by Grand Magister Rommath and other arcanists.Lor'themar Theron being in the middle of this crisis tries but fails at first to unite the two groups.All these incidents will ultimately lead to the death of many innocents and chaos will spread once more in Silvermoon.
Many external groups,both from the Horde(Sylvanas,Garrosh) and the Alliance but also ones outside the factions will find that as an opportunity to change the status quo to their favor, supporting one of the two sides secretely and thus making the situation even worse for the Sin'dorei.Both sides will use every mean necessary in order to achieve their goals (killing, making sacrifices, using powers they cannot control etc).
And so many months pass and the Sin'dorei are in total weakened state.One could say it's worse than before becomming Blood Elves.Lor'themar Theron cannot stand seeing his people dying anymore so he at last makes a more aggresive move and claims the throne because he only understands that both sides are of the same coin and that these sides combined will make the Sin'dorei glorious again.
He defeats both Rommath and Halduron in their own game and makes them see his own vision for the future (by not killing them).Now the three of them together, combing both the purity and their lust for power, are more powerful than ever.They make a campaign and make it clear to the other external groups that the Sin'dorei will never fall, cannot be used and will emerge victorious even in times of total chaos.Everyone will accept Lor'themar as the new leader since he was the one that saw the whole picture while other couldnt and the Sin'dorei will use both sunwell and fell energy in order to restore everything they lost and prove they are the best.
(players may choose green or gold/light blue color for their eyes, that way both former fans of the race (that liked their dark nature) and the ones that want the purified version would be happy)
As i mentioned it's just a personal suggestion, hope you like it.It would be nice to see other suggestions about how the story of the Sin'dorei would proceed.