Well if DFT is true, then likely we are fucked no matter what we do. The idea that we can somehow spew RF with abandon, build probes and such to leave earth and not be noticed until we grow smart enough to see back.

Seems unlikely.

... and the great ravine will be the least of our troubles, even if it kills 90% of us in trying to prepare...

My biggest reason for less confidence in DFT is my confidence in technology. Even if speed of light remains a permanent limitation, it would be logical to create a self replicating sensor network that would spread to every star, replicating before journing to the next one.

This would be different from DFT, but also quite terrifying. Basically the one "winner" race monitors the entirety of the galaxy, and would kill-off or otherwise contain any would-be competition. (In that case it might well make sense to let a primitive race progress for a period, but then stop it before it became a threat.) We could be within this window of 'no threat'. It would be logical to not provide any warning, but simply sterilize or subdue a star system once it started getting within range of real threat.

No ravine. no chance.

So those are my two leading candidates:

-- Somehow no one else is in the Galaxy, or

-- They are watching us right now with ability to easily overwhelm us anytime they choose.

not really any happier of a picture I know....