While I love 4K, I'm having a hard time justifying rebuying movies that I don't watch very often. Alien falls into this camp...it's a once a decade movie and the Blu-ray is pretty good. Granted, $14.99 isn't a bad price at all though.
Fox did a nice job on this as they did with Predator(s) and Die Hard. It's definitely an upgrade over the BD. This movie is just made for front projection/big screen.With Disney now owning Fox, I'm afraid we might not see many more Fox UHD catalog titles.
If we buy catalog titles on UHD, and there is money to be made, we will see more.
I've got the 4 movie Alien Blu-ray box set and it's a "once a decade" at best type watch (well the first 2 - the others are probably just "once"). Hard to see double dipping on it for the slight upgrade.