Do as I did, external disks of 4Tb... still hold about 15K RAW images...If you don't make a lot of pictures, this is no problem.
I have my R5 now for 16 months, and the pic counter (starting with 000) is now at about 8000. And of this I have 5k remaining on my hard drive. I delete some already in camera, another during selection. I will delete some in the future too, so storage is no issue here.
But if you store all pictures or do it professional then maybe you might have a bigger problem, yes... but if you are professional, somebody pays for it, right? ;-)