"Quite a whiles away"
"Few hundred years"
This kind of stuff is pointless. FTL travel might be invented very, very soon. Or it might not be invented ever. Colonize other planets in a few hundred years? And that's the "dream"? It could be MUCH faster, probably will be.
Where was humanity a few hundred years ago? What about twenty years ago? Fourty years ago? We have things that people a hundred years ago couldn't have imagined. What makes you think you can predict new technologies or how fast it'll all advance?
This is without even getting into what'll happen if and when technological singularity is achieved. The results are completely unpredictable, and it could happen in the coming decades, even within a decade or sooner.
I agree with you that it could happen anytime, because when one new thing is discovered, it could change the whole possibilities.
Like Gun powder did back then.
But as long as we dont unite as a world, and keep on playing our own little game here on earth, with so many problems yet to solve here, it will take us a long time before we colonize other planets.