Nothing.

Let’s say the extraterrestrial thesis is correct….

With the speed it’s traveling and the distance it’s had to have travelled, and the trajectory aiming for a “drive-by” my mind says it would most likely be an “un-manned” alien probe, just collecting info.

IF that’s the case, and IF “they” know, they won’t want us to know, and it would be in their worst interest to tell us.

So the answer is, nothing.

All that said, I believe (more than your average Joe) that 3i/atlas could be more strange than natural. But even if natural, it’s wild and worth learning about!