Correct, LTE is from the 3GPP and a GSM-based technology. But LTE is still the natural upgrade path for CDMA according to the 3GPP2 and the 3GPP.
eHRPD is just a connection interface for CDMA 2G and EV-DO 3G voice and data on LTE devices to run through the LTE network core.
GSM 2G and UMTS/HSPA have to do the same thing to run into the LTE core network; it just isn't called eHRPd (http://www.3gpp.org/ftp/information/presentations/presentations_2010/2010_05_Moscow/Core_Network_Hietalahti.pdf
And CDMA isn't old or creaky. I know this ExtremeTech article you reference says so, but that doesn't make it so. Nor was eHRPD the cause of any Verizon LTE network issues.