Now, the thing is, I was expecting there to be some warning that Merlin was about to take a powder- Nimue showing up in the medieval and space arcs, for instance. (Or how about a Logopolis-like Watcher-Nimue for the space arc?)

Nope- instead we're whacked in the temple with the two-by-four of sudden, un-foreshadowed death.

And then the two-by-four comes back around for the other temple, with the announcement that with Merlin's death we're going to skip over the two years immediately following his death for what amounts to two years of alt-universe space arc.

Don't know how I feel about all that yet- the tweety birds are still circling my metaphorical head- but it was quite definitely sudden.