[dima_vm]

Maybe it would mean "no go" to colonization at all, who knows.

For example, when all oceans boil out on Earth in 500m years or so, it might become useless for colonization. Natural resources are way easier to get from asteroids/comets/moons.

[eru]

Yes, it's not necessary to colonise planets. But you will still want to colonise around stars: they have plenty of free energy.

(In addition you can also colonise between stars, of course.)