In some of the posts that I've already made, I've claimed that Survival of the Fittest didn't need to be banned in Legacy back in 2010. To summarize my basis for this contention...
-In the wake of the ban on Mystical Tutor, pure combo decks took a hit and were also underplayed even despite that hit. Such decks were a bad matchup for Survival of the Fittest and were potentially some of the most powerful decks available in 2010, but they were just not popular enough to put up big numbers. Dredge was also capable of spanking Vengevival decks like a baby. The deck had predators, but the predators were challenging decks to play, lacked broad appeal, and it was often more rewarding for established players to just jump on the bandwagon themselves. If you can pick up Vengevival and win with it because you are skilled and because you can build an optimal version of the deck, why play a deck that is good against Vengevival when no one else is either?
-Legacy had gotten an influx of new players, many of whom flocked to budget decks and decks that were easier to play. Zoo, in particular, was extremely popular back then and was easy prey for Vengevival.
-Survival of the Fittest is just a really fun card. People have always loved it, even at times when it didn't make for a top competitive deck. When an explosive aggro-combo deck powered by Survival of the Fittest became such a powerful option, everyone jumped on the bandwagon, saturating Legacy with Vengevival decks. At other times, even when cards have eventually been rightly banned because of dominance, it has usually taken longer for a good deck to catch on so much.
-DCI bans, especially for cards that had been seeing play for a long time and were eventually becoming problematic, have usually taken a while. Vengevival came on the scene and only got a few months. If there'd been more time, the metagame would have caught up to it.
-The next few sets released after Survival of the Fittest was banned completely changed the face of Legacy, and they would have done so even if the card hadn't been banned. While the average player wasn't in a position to predict this, allowing some reasonable time to adapt would have shown it to be true anyway.
But I do have to admit, by December of 2010 when the card was banned, at least it was putting up very strong numbers. Other decks have also done so since then, but setting that aside, one could at least try to argue that Survival of the Fittest looked like a reasonable ban at the time. We discussed that point back then and I suppose that everyone made up their minds. So that's that. Believe what you will about the banworthiness of the card in December of 2010. I want to move on. In fact, let's move on to today. In March of 2017, how would Survival of the Fittest do? After all, the card was banned in 2010 and has been since then. There's no going back on that. But does the card need to stay banned now? I'm inclined to voice a strong "no." But a full analysis is really quite difficult. Complications include...
-It has been over six years since the ban. Many, many new cards have been added to the format. Six years is a long time in Magic.
-If it had just been the passage of six years and the corresponding release of sets, that would be one thing, but within that six years is included the greatest time of upheaval and evolution in the metagame. Maverick took over, dominating Legacy far more than Vengevival ever did. Storm combo evolved into more consistent lists, boosted by Past in Flames. Show and Tell went from being a mostly obscure card to being one of the biggest powerhouses in the format. Reanimator became far more powerful. Tempo decks rose, evolved, diversified, and sometimes overtook the format. And Miracles happened. The top decks in Legacy today are probably Miracles, BUG/Team America/Sultai whatever, Delver, Death and Taxes, Sneak and Show, and Eldrazi. Other than Death and Taxes, none of those decks really even existed as archetypes when Survival was banned.
-Survival of the Fittest is an extremely flexible card, as the different decks I've examined in this thread should highlight. While the Vengevival lists of 2010 wouldn't be able to compete with the top decks of today, we don't know what a 2017 Survival deck might look like. One notion is that as the pool of cards in Legacy grows, more creatures become available and Survival of the Fittest gets stronger as it can tutor for any creature. To me, it might look like Vengevine with Madness cards is still one of the strongest things to be doing with SotF, but it is largely unexplored territory.
-Some cards that would make things difficult for Survival decks didn't exist when the card was banned. Abrupt Decay is the most obvious example.
I consider it a safe unban, but I should emphasize that neither side has clear, indisputable evidence to back it up. Until the card is actually unbanned, we don't know for sure that it was, indeed, safe.