LOST Theories (will have spoliers)

[XL]

I honestly think we will get a shit ending... Except Kate who will go to jail

You call that a shit ending? I've been waiting for Kate to get her comeuppance for at least 3 seasons!!

But then they will all regain the memories in the alt timeline and live happily ever after, having never went to the island but regaining their memories and relationships in the new world.

This is kinda the thing I'm not getting. A lot of people seem to believe that Desmond awakening the ALT_Losties to what happened on the island will make them want to "back" there leading to the merging of the timelines.

My question is: Why would they wanna?

Island_Desmond had Penny but sought Widmore's approval. ALT_Des already has the approval and has now met Penny. Island_ Hurley has terrible luck and the love of his life is dead, ALT_Hurley is the luckiest man alive and has just met Libby.

Why would they want or need to go back to the island when they have everything they want/need "at home".

Obviously there are some twists and turns to come and that's all based on speculation.