So I heard about a Trademark Hasbro applied for from G1Optimal and decided to have a bit of a look into it:
Trademark Name: Combiner Force
Trademark ID: 86923603
Status Date: Mar. 03, 2016
Description: Toy action figures, toy vehicles and toy robots convertible into other visual toy forms
Owner Name: Hasbro, Inc.
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Not sure if this gonna be a new toyline which would hopefully involve all of the non scramble city type combiners, or it is to make sure no other company tries to use the name Combiner Force. At the moment it's too early to know anything but if it's gonna be new combiners, here's hoping for Raiden, Rail Racer and every other Train combiner there is :P
I'll update this when I'm needing help finding particular figures