Shoot it! IMO the MIM and IL revolvers won't appreciate much more in our lifetimes. Collector's will always be going for the older guns.
I love the new MIM S&W's and own several of them, but also IMO they are just well made shooters and carry guns. I would not buy a new 64-8 with the intent of putting it away, nor would I do the same with the M21 Classic.
Like was said, I have seen collections of handguns sold to gunshops after an older gentleman passed away, some of them unfired. The widow sells them to an honest gun dealer but still doesn't get near what they are truly worth. The guy had unfired guns sitting in his safe for decades, his wife makes a few $1,000 and someone else gets to take it out and fire it.
If they day comes when my (future)son or daughter, or my wife gets my gun collection, they will be lucky to find one with less than 10,000 rounds through it=) They will all still work, but there won't be an unfired one in the bunch.