Not changing anything soon. So, it may not be an issue for a good while yet. I'm just thinking, "If one of the components in my HT dies, I'll be looking for a new universal remote, as well."
It has been so long since I last programed it, I couldn't say.
Ideally, you could buy the same brand of component- the codes should be usable- I have posted the master code set from Denon and can provide it again, but only for comparison since your actual remote is being dropped, but the hex version is what Denon sent to me. I know AVR commands that are named the same across their line work for all models.
Obviously, availability of more recent remote models will make or break your situation.
I just checked and ebay has nine pages of various models.
On the phone with them now-
Ongoing support for database and repair of bad codes,
only HrmonyRemote V7 will end as of May 28, 2025 and suuport when using Macintosh computers. From now on, use MyHarmony software, downloadable by going to MyHarmony.com
The link shows all models that will remain operable.
Download the software required to setup or configure your Harmony remote
support.myharmony.com