So no, when we run out of sand, we'll still have lots more carbon available.
you asume that we burn through both ressources at equal speed. (ok, we don't reduce either but if we count 'we use it' i am pretty sure we would need more carbon-based material then we use silicon-based material)
What about when we run out of sand!
by this time, we will have run out of carbon too..
There are at least 7 billion sources of carbon at the moment, and that's just the bipedal ones.
Oh what a genius you are! You just solved the Problem!
You might have mail.