if i am not mistaken the correct phrase is regulated. because bitcoin is a legal currency but there are no rules set for businesses to use them. so i assume that if that day comes there will a big growth for bitcoin in adoption and as a result in price.
How about, bitcoin become an official accepted payment
That won't happen any time soon
Whatever it is if bitcoin is spread widely and many countries legalized/regulated about bitcoin payment will have big impact for bitcoin world and mass adoption, higher demand would bring us to what we are waiting for all this time. What is more encouraging than if you have a lot of bitcoin and easily spend it which has highest price than any currency in the world. 
On the other hand, Bitcoin may not yet be ready for that kind of adoption, namely, a run-away adoption as I would call it and which is what you seem to mean. Right now, it is already overstretched to process the number of transactions that hit the Bitcoin network daily. So would it be able to process twice as many transactions if we see the adoption rates hitting the sky thanks to, say, some government choosing it as an "officially accepted payment" (a purely hypothetical assumption)?
I guess the answer is a definite no