I don't see it happening though it is possible, the reason why I don't see it happening is that government is structured to be a majority wins in making a decision, so if any of the government officials ever wanted to hijack bitcoin then it will go through a bunch of discussion and as long as there are some that is opposed to it, it won't be possible unless the people that wants to hijack it gone rogue and ignores governments policy but if that happens then they're basically fighting against the government.
if Bitcoin comes to be number one currency in the world today, can it be hijack by the government?
Government can commit some unseen crime that civilians doesn't understand much but if we're talking about "if bitcoin comes to number one currency in the world" then that's a large scale crime to hijack it and UN and other countries will be involved if the government in one country decided to hijack it.