No Flash Sideways and it'll end at the beginning by Honestly Confused

I started thinking about this after reading a bunch of ideas floating around the net...and this is a first-timer so we'll see where this goes:

OK...it's all one timeline. So the flash sideways we're seeing is really just the past...sort of. Follow me:

You know how when the 815ers plus Miles, et al went back to 1977...for them, it wasn't really the past/their. In their "present," they time traveled back to 1977. That was their most recent action.

So, what if we are watching another version of the past (in the flash sideways), that is CURRENTLY playing out before our eyes. BOTH timelines are the present for that group of characters. Follow me?

So, the last episode: the current group on the island does whatever they are supposed to do and die, get off the island, whatever. As soon as they play out whatever it is they ARE SUPPOSED TO play out, the group from the "flash sideways" lands on the island to start the whole process over again. To be played in a "new" way to see if the predetermined outcome can in fact be altered, which we'll, as viewers, will have to assume it can't becasue we just saw the whole thing play itself out and then start up again.

It goes back to this: no matter what they all do, the outcome is the same (as the MIB said to Jacob). It/they always end up at the same point, they just take different routes to get there.

So the last show will be the end for the current island people but it'll be the beginning for the "flash sideways" people, who are really NOT in a parallel timeline.