I'm not going to upgrade my entire collection, even if they end up releasing 4K versions of everything. No one needs to buy a 4K version of NINJA III, for example. It's amazing enough that it's on Blu-ray in the first place.
But I am going to upgrade some films, and I'd like to keep track of them. I may keep a separate list of films I'd like to upgrade as well.
This will only be for physical media. I will not be buying streaming 4K titles as I just don't feel like the internet in my area is reliably strong enough for me to get the full benefit.