IBM today, formally announced IBM i v7.3 and v7.2 TR4.
As more news is published, I'll post links here.
Based on what I've read so far, The SQL Services (SQL UDF, UDTF and Procedures) that IBM shipps with the system, have had a few enhancements made to the existing set of services. But no new services have been introduced from what I can see. The ones that were enhanced include USER_INFO, PTF_INFO, and OBJECT_STATISTICS. These currently have "Enhanced in base" which tends to mean that they have added a couple of additional columns to the results.
The TEMPORAL Support in DB2 for i, specifically within SQL is the big new along with OLAP (Online Analytical Processing).
Aside from the above, the biggest news is that IBM i v7.3 requires Power7, 7+ or 8 CPU and will NOT run on blade servers even if they are Power7/7+. If you are running Power5/5+ systems with V5R4M0, you need to buy or lease new Power8 hardward on which to run v7.2 or v7.3 (you won't believe the speed enhancements with those chips!)
There is a refresh of ACS v18.104.22.168 from March 2016. Download it from this link.