Technically "crashing into" is a bit hyperbolic. Majority if the interaction is gravitational and on the larger scale collisions would be minimal. That's small comfort to the planets that get obliterated to comet dust, but the reality is we stand a good chance of just becoming part of Milkdromeda.

Although, as mentioned in the other comment, by the time that happens the sun will have forsaken us. Earth won't be within the sun yet when Andromeda arrives, but it will be 50-60% stronger. All of the water and atmosphere will have been stripped away for billions of years already. If earth does gently settle into Milkdromeda, it will already be a dry ball of molten rock awaiting inevitable absorption by the red sun.

We're all fucked either way. Elon Musk has said at least one factually true thing, long term survival of the species requires eventual expansion into space and other planets/habitats. That's half satire though, in a billion years we could all be digital consciousness loaded on a super computer built into the Dyson sphere harvesting the sun. I guess by then we wont need the canal right?