Was Huck going to sell Jim down the river, or let Aunt Sally, or the Widow Douglas? In 1880s America? Was Dante going to stay in Hell forever? Was Odysseus going to sail the Aegean till the end of time like the Wandering Jew until Penelope's great-grandkids were old and gray? Did you really expect that Grendel to eat Beowulf? Wait, that's actually speculative fiction, so never mind. Of course there is non-speculative fiction without a happy ending: Kubla Khan, The Mystery of Edwin Drood, The Last Tycoon and The Canterbury Tales don't have an ending at all (unless one considers the last to be a plagiarized form of The Decameron.) Then there are cases where an author sets you up to expect a happy ending just so he can jerk it away (e.g. Romeo and Juliet, or the original version of Great Expectations.) Likewise Moorcock and Lovecraft wrote a lot of speculative fiction, but happy endings are few to be found. Maybe it's not so cut and dried, eh?

Regarding WoT, I believe the Shadow has usually been poised to win for most of the series. There was an ebb and flow for a while, as a Randland filled with leaders who were myopic when they weren't selfish or just plain corrupt awakened and then responded to the suddenly real threat out of legends, and began to reverse the tide, but the DO's response once they came to nearly open war more than reversed that. What's Rand's endgame? Even he doesn't know, despite frantically researching every chance he's had since TSR. And he doesn't know about everything we do (e.g. Shaidar Haran, Moridin, Cyndane.) What he does know is paradoxical: The DO must break free to face him at Tarmon Gaidon, LTT himself says the Seals must be broken to be replaced, yet if the DO breaks free that's it, right? Maybe it's not though, maybe he'll be confronted and defeated by a Rand who can't channel and chew gum at the same time, whose hard earned sword skills must now be learned all over again according to him. While he slowly leaks his life blood out his side.

I know who I'm betting on, because I always back the good guys and usually back the underdog, but if all I cared about were the odds I'd pick the Shadow every time. The Light has been trying to tread water for most of the series, and failing for at least half of it.