Yes it's okay to teach your son to change his own diapers instead of potty training him.
If your son wants to potty train then he will eventually potty train on his own but sometimes kids love to wear diapers instead of using the toilet.
Diapers are for all ages and if your kid does not want to use the toilet and wants to wear diapers then he should be allowed to wear and use diapers.
If you do not want to change the diapers anymore then teach your son to change his own diapers and allow him to wear the diapers all the time until he no longer wants to wear them.
When I have kids I'm not potty training them either and will change their diapers for them no matter the age.
I plan to make my kids wear diapers even when they are 8 years old and will treat them as toddlers.
I want a kid just like the one in my Avatar so I can treat him as an 8 year old boy toddler and make him wear diapers and wear just the diaper and shirt and socks around the house and have him drink from baby bottles etc.
All kids should wear diapers and I think kids look cute wearing just diapers and shirts and socks.
I'm an adult baby and diaper lover myself and wear and use diapers 24/7 and my kids will too.