IBOC requires the purchase of a new receiver. There's no getting around it. Even the smallest portable model costs $40-50 in the US. A larger unit can run hundreds. This is one of the biggest problems blocking adoption. Hybrid mode notwithstanding, it renders a century of radio purchases obsolete. The open nature of DRM allows many after-market options for adapting these legacy radios to continue to work. Even your vintage cathedral receiver could be enabled without permanent modification by sampling an IF stage at one of the tubes and either routing it to a computer, or a small inexpensive decoder somewhere in/on the case.
"Aww, if you make me cry anymore, you'll fog up my helmet." -- "Visionaries" cartoon