I would argue that history is no longer written by the winners. Due to academic writing, there is a much larger interest in all sides when sources present themselves. One of my favorite books on the Napoleonic Wars is about the Austrian army and how it struggled to succeed against Napoleon. It isn't a "Austria is bad at war" or "France is so awesome" book but rather a serious analysis of why Austria couldn't succeed against Napoleon and how it addressed the problems. This type of history promotes looking at all sides of history to ensure we honestly understand why events happened rather than how. So the "history is written by the victors" is becoming less true, at least as I view history.

This '"history is written by the winners" quotation comes up a lot on this forum. Since it's at the heart of your question, I'd like to clear up a common misconception about it.

"History is written by the winners" is not a particular lesson of history, nor is it a widely agreed upon conclusion among historians. It is, in fact, a quotation from a newspaper article written by George Orwell in 1944 commenting on the nature of propaganda at the time (a perspective which would play large role in his later novel 1984).

Here is what Orwell said about the matter:

During the Spanish civil war I found myself feeling very strongly that a true history of this war never would or could be written. Accurate figures, objective accounts of what was happening, simply did not exist. And if I felt that even in 1937, when the Spanish Government was still in being, and the lies which the various Republican factions were telling about each other and about the enemy were relatively small ones, how does the case stand now? Even if Franco is overthrown, what kind of records will the future historian have to go upon? And if Franco or anyone at all resembling him remains in power, the history of the war will consist quite largely of "facts" which millions of people now living know to be lies. One of these "facts," for instance, is that there was a considerable Russian army in Spain. There exists the most abundant evidence that there was no such army. Yet if Franco remains in power, and if Fascism in general survives, that Russian army will go into the history books and future school children will believe in it. So for practical purposes the lie will have become truth.

This kind of thing is happening all the time. Out of the millions of instances which must be available, I will choose one which happens to be verifiable. During part of 1941 and 1942, when the Luftwaffe was busy in Russia, the German radio regaled its home audiences with stories of devastating air raids on London. Now, we are aware that those raids did not happen. But what use would our knowledge be if the Germans conquered Britain? For the purposes of a future historian, did those raids happen, or didn't they? The answer is: If Hitler survives, they happened, and if he falls they didn't happen. So with innumerable other events of the past ten or twenty years. Is the Protocols of the Elders of Zion a genuine document? Did Trotsky plot with the Nazis? How many German aeroplanes were shot down in the Battle of Britain? Does Europe welcome the New Order? In no case do you get one answer which is universally accepted because it is true: in each case you get a number of totally incompatible answers, one of which is finally adopted as the result of a physical struggle. History is written by the winners.

As is apparent from the context, this was not an observation about the limitations of available historical perspective. It was a comment about the pervasiveness of propaganda, which he observed playing with historical facts in ways unthinkable to prior ages.

As a result, it is VERY easy to find historical accounts which defy the "history is written by the winners" perspective. Whenever I hear this I like to point to the example of (historical "loser" and yet one of the fathers of modern history) Thucydides.