Trust me, S/36 environment is still available for IBM i 7.4
Even the RPG36 compiler is still available for IBM i 7.4.
Decades ago IBM announced that release x would no longer have the RPG36 compiler and all sorts of riots broke out.  They rescinded that announcement.
From the following:  
https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_74/rzahc/rzahcswsmedialabel.htm
B_GROUPx_02 contains the following in addition to other items:
Product		Option	Code Load ID	Description			Requires a software license key
5770-SS1	5	5050		System/36 Environment	No
5770-SS1	6	5050		System/38 Environment	No
 B_GROUPx_05 contains the following in addition to other items:
Product		Option	Code Load ID	Description			Requires a software license key
5770-WDS	31	5101		ILE RPG				Yes
5770-WDS	32	5102		System/36 Compatible RPG II	Yes
5770-WDS	33	5102		System/38 Compatible RPG III	Yes
5770-WDS	34	5102		RPG/400®			Yes
5770-WDS	35	5101		ILE RPG *PRV Compiler		Yes
5770-WDS	41	5101		ILE COBOL			Yes
5770-WDS	42	5102		System/36 Compatible COBOL	Yes
5770-WDS	43	5102		System/38 Compatible COBOL	Yes
5770-WDS	44	5102		OPM COBOL			Yes
5770-WDS	45	5101		ILE COBOL *PRV Compiler	Yes
Rob Berendt
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