You imply that the descendants of Luther and Calvin do not believe in a Real Presence, and that "the vast majority of separate assemblies that revere ML's name do not"
I have a different perspective having spent some number of years in a Baptist church, a non-denominational pentecostal church and in an Anglican church. As you have, I have some knowledge of the variety of understanding that exist among non-Catholics.
For me, the division is between those who hold the "memorial" view, that we don't actually receive Jesus (that Jesus is not "really present) in the Eucharist. The others believe that Jesus is present, although there are many explanations of how this happens. I think that the detailed explanations are not relevant here. Suffice it to say that many non-Catholic Christians believe that we truly receive Jesus when we receive at communion. Anglicans, Lutherans, Presbyterians and most Methodists believe that we truly receive Jesus. I don't think that the numbers of these groups around the world is small or insignificant. I would argue that this group is larger than those who hold the memorialist view. Even Erasmus is said to have been misunderstood in this case. Luther, Calvin and Wesley certainly believed in the real presence.
As far as the importance of apostolic succession, I would suggest that their is a variety of views with the groups that accept the Real Presence. However, they all believe in the doctrine of apostolic succession.
BOTTOM LINE
For me, it is the very loud American evangelicals who are in the minority, not those who believe in the Real Presence.
Very good points.
The two largest Christian churches or denominations in the world in order of adherents are Roman Catholicism and Eastern Orthodoxy. Some lists show Anglicanism as coming in third, others lower, but whatever the particulars, it also has a significant number of adherents, especially in some of the former British commonwealth nations, Africa where a lot of missionaries have gone and a lot of people have converted, and, of course, England itself, among other places. I've seen Oriental Orthodoxy (Also known as Coptic Christians sometimes) listed third or fourth depending on where the list is coming from. And then you start getting to Lutherans, Methodists, Baptists, Calvinists and so on and so forth. With Catholics, Orthodox, Anglicans, and Lutherans all believing in the real presence, that is very big majority of the Christian world. I am not sure where Methodists stand, it may differ depending on which type of Methodist you are- I think the United Methodist Church here in the US takes a memorialist viewpoint, but the founder of Methodism in general, John Wesley, who was originally a priest in the Church of England (Anglican) believed in the real presence, so it's conceivable that some Methodist denominations do also.
Baptists and evangelical quasi-Baptists are a very large presence in America and some other countries, but I've never seen Baptists higher than fourth places in terms of worldwide adherents on any list or survey, and often all the churches and denominations ahead of and the first several immediately behind them are believers in the real presence, except on lists that put the Calvinists around there, in which case they are often the only two in the top ten. In fact, there are a lot of places in the world where if you here someone talk about an evangelical, they mean an evangelical Anglican, which is just an informal name for Anglicans who tends towards more Protestant theology relative to their opposite theological extreme in Anglicanism, the Anglo-Catholics, an informal designation for Anglicans who lean towards Roman Catholic or Eastern Orthodox theology. Even most evanglical Anglicans affirm the traditional Anglican formulation of "real presence" in the Eucharist, though they may in some cases only barely acknowledge it relative to the Anglo-Catholics who will often openly embrace transubstantiation (the RCC view), the EO view (don't know the term for that), or something very close to those. The largest Lutheran denomination in the US is called the Evanglical Lutheran Church in America, but they believe in consubstantiation, a form of the real presence, just as Martin Luther did.
Actually, it is kind of weird how much these lists vary, but I guess there is a lot of incomplete data and that there are lot of judgement calls involved with deciding what group some individual churches or denominations actually fall into when they aren't a formal member of a large institutional church. There are so many splits and mergers and small regional churches, and not all of them have something obvious in the name that tip off what family of churches they resemble.
I think the lists that show Anglicans in third globally are probably thinking of churches that are one institution or communion, and counting the Anglican Communion as the third largest institution, which it probably is. On lists where Baptists rank highly, they are probably grouping a lot of completely independent denominations that share beliefs and naming terminology together in "families" to figure out what is what. For example, on the first type of list of institutions, when we say Roman Catholics, we'd just mean Catholics in union with Rome. On the second type, we'd toss in Old Catholics, the Polish National Catholic Church, SSPX, and all kinds of groups with Catholic in the name that maintain practices like Apostolic Succession, seven sacraments, veneration of Saints, etc..