Extinction in 10 or 20 years would be regarded as being roughly equally bad - since these are small figures smaller than the lifespan of humans and within their planning horizon. So an evolved creature acting in their genetic self-interest can be expected to regard both outcomes as being roughly equally bad.

People don't act in their genetic self-interest alone, and myself, I'd very much rather die childless in 20 years than die childless in 10 years.