It's not impossible, but I would still say it's unlikely. Here's the thing a lot of people don't get, just because it's currently impossible for humans to do it, doesn't mean aliens don't have the technology to achieve it. However, you need to ask why aliens would come here? To a culture advanced enough to travel vast distances, we would appear to be irrational apes, playing with archaic tech. The last thing I'll add is that if they did come here, they might be less interested in communicating with us and more interested in dolphins, whales or octopus. They won't look anything like humans. It's more likely that they would have virtually nothing in common with us. However, never say never. It would be very cool if someday it happened.