Not that it's going to be exactly the next big thing but as now there is a trend to do apps on the cloud javascript
is getting a lot of interest as is the de facto standard for browser scripting.
Also there are many pages trying to measure the popularity of programing languages (some examples):
- Programming Language Popularity Chart
- The Transparent Language Popularity Index
- PYPL PopularitY of Programming Language index
- The RedMonk Programming Language Rankings: January 2013
- Trendy Skills
- Programming Language Popularity
Those are not GIS specific but most of those top programming languages had their GIS libraries.
On the other hand if you check here the popular tag listpopular tag list you can see that after python is openlayers (that means javascript
) and then postgis (so SQL
would be interesting also).