It is a big adventure for sure, and there are plenty of questions about the likelihood of the canal ever being built. See: Doubts deepen over Chinese-backed Nicaragua canal as work starts
In my memory this has been talked about for three or four years, but they are getting closer to really breaking ground.
With all my other blog posts about critical infrastructure here in the USA and its poor maintenance and replacement process, it would be a good "stick in the eye" of America if they can pull off building the canal. If the Chinese government is really bankrolling the enterprise there is no reason they could not do it. They are undertaking much larger projects and completing them in their own country.
If you don't know it, China is all over Africa. While we twiddled our fingers, they have huge business interests all over that continent. We have ceded any influence we might have had to them. They now "own" a great deal of influence there. Building the Grand Canal would give them a significant foothold in Central America.
It will be interesting to see at what point Congress stops debating repeal of Obamacare and wakes up to its other responsibilities, like passing a real transportation bill instead of the stop-gap measures that have been taken since the last one expired in 2009 -- six years ago!