As for "Lost"...
SPOILERS AHEADAs for the "game-changing" aspect of the "flash-forwards", well... First of all, I had never come across the term "game-changing"... Cool!
Secondly... After watching last night's season finale, it really has set up the whole time on the island as one big flashback. The "flash-foward" scenes with Kate and jack were obviously in the present. -I loved how people - even my roommate - pointed out the brand and style of cellphone that Jack was using. Now, we just have to figure out how far in the "future" the flash-forwards took place. -And I think future-Kate is with future-Sawyer.
As for why "the Hobbit" allowed himself to die, well... I think he was basically fulfilling Desmond's visions, and he just wanted to stop stalling whatever "process" was/is in motion. Additionally, I think he knew that if Desmond had run into that room, then Desmond would have most likely died too - and by that time the equipment was already flooded out. Also, by closing that door, he prevented the rest of the Hourglass from being flooded out too - the grenade only blew out the porthole. Thus allowing Desmond a chance to get out of there.
As for whatever will be happening over the next three seasons, well... I'm wondering if this was the "hook" that hooked the ABC execs when the creators pitched the show. I sense the real story will not start until we get off the island. Subsequently, the title "Lost" takes on a much larger meaning.
OH! And I also have to wonder if Locke's paralysis has been psychosomatic all along. Maybe the plane crash just made him "forget" all of his troubles; the drastic change of scene gave him a chance to start fresh. And when Walt(!) told him to get up, and he could... Hmm..
