[toni-a]

This is a subject I haven't heard or read much about in a long time. DNG was going to save us all if I recall. ? To date, I don't know of any raw format that can't be converted one way or another. Most, if not all, are still covered by the big players. There's not that much code to carry along (probably for my lifetime anyway). I also don't believe you'll ever not be able to convert a raw file. Besides the big players, there's plenty of open source code and plug-ins (rawpy) out there. Which makes it easy to convert all your files to something else, provided you have the disk space to save it all and don't mind writing a handful of lines of code. But it all leads to essentially your second question; how do you do this in a timely manner?

TBH however, at this point I'm not even sure how to go back and really look for or browse all my old raw files. Everything before the last 10 years isn't easily accessible either by finding it or remembering it.

My methodology for this, and take it with a grain of salt, is to keep all the raw files along with edited files I printed or shared. If they're just vacay/fun shots I printed or shared on social media, I delete most those. Nowadays, the saved edited files are full res jpegs being I generally print jpegs. I also can't see jpeg going away anytime in my lifetime.

JPG is staying for sure,  but keeping the original RAW files, is still very important, newest version of DXO with AI noise reduction helped me salvage old photos of my daughter as newborn that were too noisy to be considered as keepers, AI noise reduction works only on RAW, were they JPG I wouldn't have been able to do this.

As for DNG, a DNG converter will always be available and I don't see the advantages of DNG versus native RAW files, and since Canon DPP is my preferred RAW converter ( it doesn't work on DNG), I am keeping CRW, CR2 and CR3 files, besides Artificial Intelligence based noise reduction is now  included in DPP however for selected new cameras, if compatibility is extended to all models just like they did with DPP4, I might well be extensively using it on some old files .