There is more oil traded in a day (in terms of market price) then the market cap of bitcoin is. This would result in constant huge swings in price of bitcoin as people try to move in and out of oil.
These factors will change. The dollar will loose liquidity and bitcoin will gain liquidity (massively). Of course this will not happen overnight. Step by step "apostate" countries will leave the dollar sphere, thereby decreasing the importance of USD as reserve currency.
You're reversing cause and effect in your argument: The USD is widely traded and liquid, because oil is traded in dollars. Not the other way around.
Yeah, things would be quite a bit different if oil was traded in a currency other than USD. That is definitely one of the major things that support the USD's spot as the world reserve currency.