If this actually results in a stronger, more unified service to rival the big players (Netflix, Disney+, Prime Video), I'm all for it. 4k content, 5.1 sound, hiring some UX people; sounds great!
If it's just a quick cash grab for Sky to get more revenue now that it no longer has a stranglehold on content, well then RIP Lightbox.
What makes you think Sky will invest in app improvement. They currently don't. 720P and stereo sound is here to stay :)