This is just speculation, obviously, but it strikes me that the early emphasis on Claire and Kate means that this will somehow involve Aaron’s role in all of this. Whether Aaron in the “other timeline” (Lindelof and Cuse don’t want us calling it “alternate,” as it is, to them, an equally valid course of events to the primary narrative of the show) ends up becoming Jacob or somesuch, who knows? But, for me, this is working quite well so far to set us up for some interesting final explanations.

You’ve nailed the major problem that I had with this episode. And I think you’re also correct that, when these two storylines inevitably converge, the episode will be more interesting and satisfying in retrospect. But right now, the “LA X” timeline almost feels like non-canon, speculative fan-fiction–a narrative strategy more interesting conceptually than in practice.

Of course, it could just be that I prefer LOST at its most relentlessly bonkers. A Tim Burton-esque, Syfy-quality dive into the ocean, revealing the sunken island? Yes, please! More of Kate’s adventures as the fugitive with a heart of gold? Eh, fine.

So, to my eyes, this is opening up new questions and setting things up, but is already starting to pull together a number of things from the series into a ball and rolling it down a hill toward an answer. I’m curious to see where that will take us.

Very much a “table-setting” piece, this one, and that’s OK, for the most part. There are clearly ideas and nagging issues that they want to put out there and let simmer for a bit as the season goes on. This pacing is actually most strained in the temple sequences, where we have the very familiar scene of Jack wanting answers and the Others trying to distract him (and us) with wordplay. We’ve seen this time and time again, and at least they upped the ante by having Jack take the pill, but still: they’re stalling, to allow the question of the “infection” to grow, and (presumably) to allow time for Smocke et al to come to the Temple (which looks like will kick into gear a bit more next week).

And here’s an interesting thought for next week. Given that it’s presumably about Sawyer, what is this alt-Sawyer like? I wouldn’t be surprised to see Cassidy show up in the alt timeline, which puts an intriguing spin on his commitment issues.

One thing I will point out is that the episode serves another important purpose of memory: not only is it referring to Aaron’s back story, in terms of the birth in Season 1, but it’s also the first time we’ve seen Claire in a very, very long time. Outside of a brief moment last week, we haven’t spent any time with de Ravin, so for viewers who haven’t been compulsively watching old episodes before each new one it’s important to remind them of who Claire was before we discover who Claire is. It may not have been a mind-blowing flash sideways, but it was an integral one to be able to reintegrate Claire into the narrative.