Personally I'd feel confident my kids could get to Alpha Centauri if people stopped being so greedy and wasteful and we actually focused on it as a goal, although I believe we have more pressing issues, I'm sure we'd at least get something non-manned there.
But without that, without that fantasy, it'll be much much much longer.
I'm afraid you're probably right - although, as I'll discuss in the next post, even with all of humanity backing the project, interstellar travel is anything but assured.
Why Alpha Centauri? Isn't the Trapist system closer?