One thing to keep in mind that adds to the improbability of colonizing another planet is the fact that it would likely require the entire planet to work collectively towards that goal. Pooling resources and brain power and working as one, because no single country would have the money or man power to accomplish that.

Spend 5 minutes in social media and it'll be clear that we could never achieve that even if all the stuff you mentioned wasn't a factor.

Interstellar transport.. I wish. We can't even get a living human on the next closest planet to us let alone out of the solar system.

We are almost certainly going to go extinct long before we get to another star's orbit.

Yeah, that's probably about what will happen. As it stands we're what, 50,000 years from the next ice? And all of like...4 years from a blue ocean event that's going to drastically accelerate that.

Well, until the sun goes supernova anyway, isn't it expected to swell beyond Earth's current orbit of the sun?

Speaking of, is that supposed to happen before or after we collided with Andromeda?