Rede- Is it not the point that it would be necessary to have invented warp drive (or something similar) if the anticipated mass extinctions (for whatever reason) happen?
Yes, it's certainly the point.
"Objectively, the desired breakthroughs might turn out to be impossible, but progress is not made by conceding defeat."
"All NASA support to sustain cognizance on these possibilities has been withdrawn as of October 1, 2008."http://www.grc.nasa.gov/WWW/bpp/index.html
I see it as rather like Charles Babbage trying to figure out how to build a Blue Gene supercomputer. We need a whole range of new technology to support an interstellar colonisation mission. It's not even a 'simple' matter of inventing a suitable propulsion system.
This particular research could probably be carried out far, far more effectively and efficiently within another 50yrs, given the logarithmic acceleration of global technological progress. Who knows, by that time even a the fictional warp drive may appear more realistic.