Like maybe if the Wilson Island Mammoths [1] had just a bit easier time of it, or their populations weren't quite as small (or by luck of the dice were much smarter!) then they could have survived.
In fact it would have really helped elephants if some of them were smart enough not to be made extinct by humans! Maybe if humans had been just a little less competent, pressuring but not exterminating the wooly mammoths...
E.g.: humans could reach high technology relatively easily because our environment and physiology enables tool use, etc…
But if “takeoff” is blocked, and evolution continues, then it might still be possible for an aquatic species to overcome the limitations of their environment — but only once they’ve reached the much higher level of intelligence required to find workarounds for their miriad problems!
Since elephants aren't carnivores I don't think they would get much benefit out of the reasoning skills that enabled us to be really excellent pack hunters, which was probably why more intelligent ancestors of humans managed to out-compete the less intelligent ones.
If elephants gain abstract reasoning skills what does it get them? More efficient harvesting of bananas?