Tron has way too many opticals to make for even a moderately decent UHD. Plus, it's Disney, which means a physical release is unlikely. The "Special Edition" Blu-ray (from 11 years ago!) is a pretty solid release already.
Sigh. Yes, Paramount released Dragonslayer in the US. Disney didn't. That's why the cross-discussion of Dragonslayer and Something Wicked... is causing confusion.
As for not imagining it won't be awesome, it's Paramount. They've released spectacular UHDs/BDs, and piss-poor UHDs/BDs. I'm hoping...
He might be getting mixed up in the cross-discussion of Dragonslayer and Something Wicked This Way Comes. The comment regarding Bradbury on a commentary track was about the latter. Disney, of course, didn't release the former on LD in the US. Only in Japan (albeit pan-&-scan; I have a widescreen...
I doubt very much that Disney would be interested in releasing a UHD of Something Wicked This Way Comes. They didn't even release it on Blu-ray in the general market: it's a Disney Movie Club exclusive.
Funny you should mention it. I was going to say that I've always felt that the SFX folks on that film were inspired by Dragonslayer in their design and movement of their dragons.
I like Reign of Fire, too, but I don't feel particularly guilty about it.
There's very little chance of seeing Tron in 4K. There are far too many opticals getting in the way of a decent 4K presentation. But as far as the other three you mention go, I would say that Excalibur is the only one that I think might be better than Dragonslayer. Might. Clash of the Titans I...