Yeah, that was me who started that thread about the catalogue being updated - but that's only covering the first half of the year and although we know some of what's to be expected in the latter half, such as Dark Justice's hardcover, we don't know all of it;
but Keith Richardson dropped this message on the forum in reply to someone asking after the Complete Edition of Ro-Busters meant to have been released last year (quoted here, but you can click the link to the actual thread): "Ro-Busters will be split into two volumes, the first coming out later this year. Yes, it will be sporting a brand new cover from a legendary art droid. Yes, the colour spreads will be included."
So it's the same thing that has been done with the first two Mek Files volumes, a series of books I'm sure will also be continuing. As I said - and especially because Pat Mills' collected editions have been the best books 2000AD have published - I have a suspicion that we could see other Mills work collected in similar volumes next year, or after these two series' are brought up to date.