Yes, prolonged baking (or even letting the bread cool down in the turned off oven instead of taking it out) will dry out the bread. I can confirm it from my own experience.
I doubt the idea that the internal temeprature will keep down at 212 F. This is true of water in a bowl, but the moisture within the bread is not a puddle of water. It could turn to vapor (which can easily get hotter), in theory it could superheat (although I don't imagine that happening in bread), etc. And even if the water itself stays at 212 F, this is no reason for the solids to keep at that temperature, the water will cool them somewhat but not to the point of full equilibrium.
And even if the temperature would keep at 212 F, this is no reason to assume that this would prevent the bread from drying out. Starch gelatinization is a complex process, which goes at different speeds at different temperatures, and the water itself, if kept in equilibrium at 212 F, will be slowly turning to vapor, and this vapor will be slowly evaporating from the bread.
Bread with very dark crust is not made by prolonged baking, professionally it is made in higher temperature ovens, and with some additions to the dough (malting enzymes). If you try to use prolonged baking instead, you may get darker crust, but you cannot avoid drier bread then. I have not read any of the sources you reference, and tend to bake my bread by the oldschool books, this means removing it when the internal temperature reaches somewhere between 96 and 98 C.
I have never connected a shiny interior to full gelatinization, for me it tends to happen when I have higher gluten content. Maybe there is some connection, but if yes, I am not aware of it.