Tonight I've worked my way through some of accelerando, charles stross' book about a future where the singularity happens.
Kicking around in the back of my head is the idea that both things will happen, the ecosystem will crash while the singularity burns through the remains of carbon based life and transforms everything into computonium.
This version kind of reminds me of one the first terrestrial singularities, back when a handful of bacteria figured out photosynthesis and trashed the ecosystem by filling the atmosphere with a deadly toxin (oxygen).
Descendants of the anaerobic bacteria are still with us, but they live off in the margins of the oxygenated world. I have a hunch that the future will look like that as well, most everything interesting will be happening as computation, while traditional organic life struggles to live off in the crevices.
(I sure make a funny green party member).