Python in Excel looks interesting. It’s only in public preview now and will go Windows first so I won’t see it for a while.
Python has some really awesome tools for analytics and plots. Although it probably won’t ever be a mainstream tool, many data analysts are going to be all over this. I’ll definitely take a look when it’s out there.
I played around with openpyxl a few times and it has some usefulness but is not as tightly integrated as the new =py() function. I guess we will see.