Is there a way to supplant/eliminate my old @mac id for the newer @icloud email?

I’ve recently retired and was hoping to leave my old email behind. I still get thousands of vendor/business and unsolicited emails that I would like not to weed through for the rest of my natural life :) Is it possible to simply use my existing @icloud account as my “main” Apple and iTunes ID to accomplish this?

I know I can simply use this account but I would like to delete the old account entirely rather than hide it? Casual conversations about this at the Apple store have indicated that I can never eliminate my @mac account unless I’m prepared to lose 25 years of music/movie/book purchases.

Anyone have any suggestions?

Thanks!