The network will not merge sections now. With the design of Elders and many adults per section we would need to lose nearly 90% or more of data for a merge to occur. So we don’t need to merge sections now, unless we lost all that data and that is end of network and breaks fundamentals. It also allows a linear progression of prefix management whereas merge would require a more complex mechanism for holding section history and so on. So the merge code (a nightmare) is not required or cannot be used. It allows us to move faster as well not having to do that.
tl;dr the network can lose over 80-90% of nodes and not have to merge, but a loss of that proportion means significant data loss and that would be the end of the network. Later with archive nodes this may alter a bit, but only if it can be altered and still protect data.