As a former Army Chinese linguist I will make a few arguments for chinese, that you may not have thought of.

1) There will always be a demand for Chinese, no matter how many linguists there are there will never be enough.

2) The Chinese are always very gracious and there are Chinese communities everywhere. While this is true to greater or lesser extents with any language, the near ubiquity of "Chinatowns" throughout the world means that with Chinese, you have a foot in that door. More importantly, as you have hopefully learned with your other languages, knowing the language goes a long long way towards respect, and that is especially true with Chinese.

3) China has a ton of movies, many of them good, and most of them available through Netflix or online, and sometimes even Redbox or Blockbuster depending on where you live.

4) Chinese food is really good, and it can be a lot of fun going to the places that your Chinese speaking partners know.

5) You will never get a tattoo that says something you don't understand, because it looks cool, and you will know what all the idiots around you have tattooed on their backsides.

6) There are a lot of really good students from China, who it is very useful to know. If you know their language, they will seek you out. (This is not about 'asians are smart' or anything like that, just that many of the best students from China come to the US for an education.) I have had several very well known visiting professors seek me out for assistance, and help me in turn, only because I speak Chinese, even though I am a grad student.

Then I have to give the one drawback.

1) Chinese is easily the hardest language I have ever learned, and I speak six including Arabic. This is because there is no alphabet of any kind, and there are 60k+ characters. That is a lot. However, that is also the reason for a lot of the things that I was talking about in the plusses. If you climb a big mountain, you will get rewarded with a great view.