[Silmiel of Imladris]

I think that is one of the reasons the elves were so eager to leave, they knew what could be coming. In my opinion if Sauron had won at Minas Tirth and found the ring he would have destroyed evey other civilization first like the men, hobbits, drawves. He would kill off everyone else who could possibly stand against him and then he would have started on the elves. He knew they were powerful and many other races would be willing to help them so killing off their allies first would be the doom of the elves since there were so few of them left. Besides Saurons main campain was destroying to world of men, the small number of elves he could get later.