Once Sasquatch has been proven to exist, I predict it will be natgeo or animal planet or some other animal related group that makes an official announcement to the press. NOT our government.
As I've eluded to in other bigfoot related posts, I, and many others, believe the government is already well aware of the existence of a tall hairy man-like creature traipsing around in the backwoods of the USA. There are simply too many stories, accounts, and too much evidence out there to ignore this probability.
Therefore, if someone managed to capture or kill one and get the pix, video, and DNA info released to the public before the government can quash it, I believe in the short term you will hear very little from the government by way of " announcement ". I suspect that the government, at least in the beginning, will do its best to distance itself from the situation and pretend it's not interested. If a new species of bird or rodent was discovered, the government wouldn't make any kind of announcement. So I doubt discovering bigfoot would be any different.
Eventually though, animal protection groups would raise hell and a government backed official scientific inquiry would have to be fired up to determine where they live and how many there are. This research alone will take a few yrs, because they will not suddenly become easier to locate just because one got caught or killed. The only advantage would be that resources would suddenly become available to researchers that never were available before Sasquatch was proven real. No scientist or research lab would avoid helping once the myth stigma is removed from the subject, and instead groups would come out of the woodwork to try and be the first to gather solid info on these creatures in an attempt to garner fame as a result.
Now let's jump a couple years into the future. Let's assume we discover that many of our state and national parks are infested with bigfoot, and that they are scattered everywhere across our nation, some areas will be ordered to be set aside as protected bigfoot habitat. I don't think this is avoidable. While there will be some pissed off people and corporations and industries that will take a hit from this, I don't think it will be as wide spread and disastrous as many people predict.
In many folks' opinions, this situation is one of two primary reasons the government is keeping its knowledge of Sasquatch a secret; the fear of the resulting economic problems it would create. Worst case scenario....lumber and paper supplies would halt, home building would all but cease, then the financial hit our national parks and surrounding communities would take as a result of vacationers avoiding camping and hiking and fishing where a real boogie man is known to live. While I personally doubt that Bigfoot being officially accepted as a living species would result in all the economic problems listed above, it would no doubt have some negative effect on a few industries.
The second reason the government doesn't want bigfoot to be proven to exist is that someone would accuse the government of being culpable in regards to thousands of missing people who have disappeared from our national parks over the last hundred years. Once it's publicly known that the government knew that Bigfoot was sighted nearby, and that evidence found indicated weird circumstances were at play in many of these disappearances, someone at the dept of the interior is going to have to answer some hard questions in congressional hearings. The US gov would much prefer to avoid all that I suspect.
Therefore, don't expect the government to be all excited and anxious to make announcements once bigfoot is PROVEN to exist.