«…Will vast swathes of code have to be rewritten as those modules become unmaintained…»

Sure. This will happen. Because of some visions like this i was very unpopular in the famous last company i was with. See also Cassandra for further details. In German we say: «Ich habe es kommen sehen!» It is like in real life: «They» always tell us that «this» will never happen. But shit happens. Like the tragic flood in Germany recently or the total disaster now in Afghanistan. Regards, Karl