The attempt to publish a pre-1955 Missale Romanum seems to have hit a massive wall, if the publisher's website is any indication. The publisher moved from a pre-order policy to a commitment to order policy, but the crowds just aren't biting on this one.
The sedevacantism of the group behind the project is partly to blame. For those of a Western liturgical persuasion, sedevacantism can be an exciting place - the closest thing you'll get to the phenomenon of independent Protestant churches with a Latin liturgy. It can also isolate you pretty quick.
More probably, however, is that the demarcations of the traditional Latin liturgy have been defined along the lines of Missale Romanum of 1962. Probably by the sheer force of Lefebvre's group having established its liturgical identity around said missal, it is almost impossible to introduce another addition into the the discussion and certainly impractical to try publishing one. Rightly or wrongly, the Missale Romanum of 1962 IS the traditional Latin liturgy - it has no other real competition.
There are, of course, criticisms that have been made about the Roman Missal of 1962. How substantial these criticisms are versus how academic depends largely on one's persuasion. Yet, any criticism is highly theoretical in light of the complete absence of viable publishing options for the pre-1962 books. Without the publication and presence of usable copies of the older editions (pre-Holy Week reform, pre-Signum Magnum, etc.) any discussion of using them is strictly in theory.
The greater mass of people interested in the traditional Latin liturgy either have no knowledge of the older books, or no desire for them. Practically speaking, not many will notice much of a difference. It makes it hard to make sustainability case of the pre-1955 missal. The interest in said missal seems to border on the lines of eclectic...if not esoteric. For anyone with a historical perspective on the old liturgy, this is a lamentable state of affairs.
There are limited avenues here and there. While there are some legitimate criticisms of it, Antioch's Western Rite follows the rubrics of the 1950 Missale Romanum. This said, be forewarned: you'll have to stomach a descending epiclesis and the number of Western Rite parishes using it is limited (most work off of the Book of Common Prayer).
Arguing for a substantial difference between 1962 and a previous year is a hard sell. Perceptively, the differences appear negligible and it is debatable if the changes between 1962 and the previous editions sufficiently alters the experience of the old Latin liturgy to effect the sense that one has experienced something else. This is crucial. Experiential knowledge holds significant sway. I have thoroughly experienced the Missal of 1962. Whatever academic critiques I may have, said Missal has created and cultivated my conceptualization of the old Latin liturgy.
Any attempt to enlarge the scope of the phrase "traditional liturgy" or "Latin Mass" faces the challenge of demonstrating that there are sufficient enough difference to demand the inclusion of early editions of the Roman Missal. When put to the test, most of the arguments appear to be somewhat ethereal - of crucial relevance to liturgy aficionados but hardly able to be transmitted as something of concrete urgency.
Should the discussion include earlier editions of the Missale Romanum? Absolutely, but don't be surprised if the earlier editions (much like the other Latin liturgies) remain the interest of a limited few with little prospect for actual implementation. So far as concerns implement the traditional Latin liturgy, that debate has largely been settled. The Missal Romanum of 1962 is the dominant usage and therein lay the challenge. The next venture has to be in area of defining the variety of uses of the old Latin (in this case, Roman) liturgy, thereby removing the obsession with liturgy by regulation.