While the interest in 1970s comic collecting is still quite active I'd like to see made real the opportunity for people to finally 'complete' their collections with the publication of these unpublished but completed comics from the '70s. Ideally a facsimile approach as has been used for a few selected reprints recently, that particular month's ads and editorial filler inclusive... especially any letters page that could be found which was readied at the time, would be my choice (although with a modern cover price and bar code naturally).
As I understand it, DC had these following six comics prepped and ready to roll, even advertised, when these titles were suddenly cancelled:
Vixen #1
Firestorm #6
Black Lightning #12
Kamandi #60 & 61
Shade #9
Showcase #105 & 106 starring Deadman and The Creeper were similarly prepped, but their stories were used in slightly altered form in dollar titles of that time and collectors of '70s comics would almost definitely have those. Firestorm #6 was once included in a much later collected edition, but for people who have the original five comics that makes most of it superfluous as well as being in a different format.
As well as being allowed to read and enjoy them in the form they were meant to be in, decades after they were promised in editorial hype at the time and/or at the ends of the issues before, for me such regular comic book format editions would be filed with the original '70s comics, finally completing their runs!
The covers of three other such cancelled titles are known to exist:
Mister Miracle #26
Ragman #6
Black Lightning #13
If there were interiors at least started and still existent they would be as welcomed even if only completed now. There were mystery and war comics also cancelled in the late '70s, but as other general mystery and war titles continued I suspect any contents found homes in the same fashion as the two Showcase issues did.
Marvel also had at least one '70s title produced and in production when it was cancelled:
Ms. Marvel #24
Although this was included inside a giant-sized various features '90s comic, even that is now becoming costly (due to what would have been the second appearance of the popular villain Sabertooth), and again, filed under another name and in a different format. There was also an #25 started but only completed later in the '90s that also could appear under it's own separate edition.
I'd definitely pre-order a copy of each of these at a modern price given the chance. I'm certain they would be good sellers, equal to the most popular '70s facsimile editions that have started to become highly valued with prices multiple times the cover amount being asked on some such as Batman #251, Hulk #180-182, and Giant-Size X-Men #1.
Other facsimiles, or at least individual comic book editions, I'd like to see would be '50s (and even '40s) Atlas/Marvels... starting with the Bill Everett Sub-Mariner revival starting with #33. I was excited by the facsimile edition of The Black Knight #1 by Joe Maneely & Stan Lee and notice it has started being resold at higher prices perhaps from demand of people finding out about it's existence after the fact. Some of the late '40s Marvel heroines had equally high quality art; The Blonde Phantom, Namora (connected to The Sub-Mariner), and Sun Girl (connected to The Human Torch) could make for a theme series of facsimile editions of first appearances and the first one to three of their solo title.