It just occurred to me last night that the 1965 Ordo Missae, sometimes called the "transitional missal", has been completely overlooked, so far as I know, in the entire discussion of Summorum Pontificum. Here we have the Ordo Missae that immediately followed the Council. It kept the old form nearly entirely in tact but for the introduction of vernacular and some other small trimming and change. It was short lived and appeared in a time of great liturgical experimentation and confusion, and was displaced 5 years later. I've never entirely understood why it didn't seem to have much impact on history and now seems entirely forgotten. But not everyone has forgotten: here is one blog that believes that this, or something close to it, points the way to the future imagined by the Pope.