Well, damn. It’s gonna be a long wait until season 4, as I’m sure they’ll leave us hanging.
I wonder if that’s really it. I know I’ve been hoping for several months that this was all leading up to the universes merging because the implications would be facinating (Charlie, Broyles, Peter, and Olivia’s family would be okay, but what would happen to everyone with a surviving twin if the two universes merged?), but I’ve never really gotten the sense that they really plan to go there.
He looked like he’d gone on a bender with Charlie Sheen at first, and it took me a moment to realize he was supposed to look older, but I guess it was pretty good.
Are you saying going on a bender with Charlie Sheen wouldn’t age a person? 
I don’t think merging the two universes would be a satisfactory result. Both sets of characters have their own lives and a merge would wipe out both lives creating a third. Maybe the writers could make this seem like a happy ending but I don’t know.
From the preview for the finale, Peter mentioned:
Doomsday
I’m not sure what this means, but I’d say it’s pretty likely it’s whatever goes down in 2026. I have a feeling next season will finally incorporate what the Observers have really been driving at. Perhaps not their origin, but maybe their goal? Somehow these two universes were never supposed to cross paths, and they know it (and perhaps didn’t realize it would happen until Walter effed with things?). If the Observers aren’t infallible (and it appears they aren’t), then they’re trying the best they can even with the huge scope of knowledge of future events they have to repair whatever it is they think needs repairing. It looks like they’re afraid they might not succeed. And if they do, it might mean really bad things for both sides. Perhaps the ultimate fight is against the Observers?
They must’ve planted those Machine parts far back in the past knowing both sides would need to gain access to them. Peter’s so special because he’s the only human to have been torn from one universe that greatly altered the chain of events in both of them, much to the Observer’s dismay.
My guess for now, anyway.
And what’s with the Observers and their love for capsaicin?!
Their senses are dulled so most food is flavorless to them. So they order super spicy foods to try and get some flavor.
I didn’t even notice Peter looking older. I guess I was too busy just trying to make sense of everything. I pretty much had the same thoughts as everyone else here - that either the two worlds merged or that at some point in the future, a Fringe Division akin to the one in the alternate universe was created in the regular one. I guess we’ll find out next week.
On my DVR, the summary for the finale says that…
a team member bites it. I’m worried about Astrid and Broyles.
For the bulk of this season, I was hoping that the alternate universe would end up being destroyed, and that one or two survivors (people whose counterparts don’t/no longer exist, i.e. Charlie, Olivia’s baby) would make it through to the regular world. I could totally see alternate-Charlie coming over and having to learn to adapt to our world. I’d even be okay with a character merging with their counterpart (like Lincoln maybe), because that could lead to some interesting stories. But having the two worlds merge totally would not be acceptable. I guess if they end the season that way and resolve it early next season that might be okay.
So far I have no complaints about the show, so hopefully next week won’t let me down.
Ooh, here’s a thought - the machine has indeed merged the two worlds, and the battle that future Peter’s fighting is against ALIENS!
Whaddya think?
Hey, why not?! 
But in all seriousness, I don’t see the show going down that path… too X-Files for comfort. But… I WANT to Believe!™
Yeah, maybe you’re right - limit the weirdness to parallel universes, time travel, and mind powers. I’m guessing the Observers have to be either from the future or aliens; since Peter seems to be time-travelling, I guess from the future is the answer.
Technically, it’s piperine that they love - that’s the active ingredient in black pepper. If they were capsaicin cravers, they’d be sucking down Naga Jolokia chiles. 