I imagine so. I don't suppose they would 'remove' anything as far as 'extras' go - unless with very good reason - as surely this would require them to re-author the discs (or something!). And as this repackaging seems to be part of Network's money-SAVING strategy...
Once it comes down to an even better price, I'll buy it and put the huge +book edition away in the back of a wardrobe for safe-keeping.
No, don't worry; these disc holders are completely different. They are just standard disc trays - exactly the same as in the Space: 1999 (year two) blu-ray set, although the case on the UFO set is about half the depth of the 1999 one. Didn't really compare the inside of the sleeves, containing the disc info, but the design does look different; conventional inside front and inside back layout as opposed to presented sideways across the three inside surfaces as before. All the actual text on the packaging looks identical to previous set. All disc menus and disc surfaces look identical too.
As with the UFO 2016/2017 sets above; here - for those who have them - are comparison photos showing the difference in size of the new UFO blu-ray set, the Space: 1999 Year Two set and the Invasion: UFO set.
(It seems that Network are desperate to get the blu-ray and DVD packaging down to as small a size as possible - I'm actually surprised that they have managed to fit an entire series into a case that's so slim. In some ways this is more convenient - for those with ever increasing collections and shrinking shelf-space - but it seems that the days of the extravagantly packaged box-sets might be numbered. Cheaper on postage too, of course! The new UFO set is certainly easier to handle than the previous one.)