I'm in the "merging of mindsets" point of views with the LA X time line as the epilogue after the BIG war and sinking of the island---- Whomever against whomever in an epic battle. . . ..
But for the ALT things, I encourage you to be less frustrated.
Imagine at the beginning of an episode soon (from the perspective of a screenwriter)-----In Alt LA X--- Dogan wakes up in pain in Jack's hospital confused, paranoid, looking at a syringe nearby ready to attack someone. . . he sees Jack come in and says, "Sheppard. . . the Island, what happened?" Jack says, "What do you mean." Jack is confused but shows some slight memory in his face. Dogan says, "I was. . . what . . Jarrah? The healing pool... What. . ." He somewhat composes himself and looks around knowing he is off the island. Jack says, "I met you, at our sons' piano thing... He's here, wanting to see you. I'll be back later." Jack leaves as Dogan's son comes in and embarrasses his dad. Dogan is so happy and cries and says, "Jacob, you did so much more than you offered.
When his son leaves, Jacob comes into the room and Dogan, though still confused, thanks him in Japanese. Jacob replies, "It will take you several months to merge your memories--- you have two lives--- the Island and here. It will feel normal later. Don't tell Sheppard you know him until you see him in about a year. I'll make sure you get an invitation to his wedding." . . .
Similar event happen when the others are killed on the Island.
A year later all come together (last 10 minutes of series)------ it is Jack and a pregnant Kate's wedding and through all those connections ALL the characters are there--- all the cameos. Sayid now with Nadia as his brother was killed by a "bigger boss" revenged by Sayid again, but still-- all are happy. . . All great knowing each other there both Island and LA X minds combined---- Sawyer with Juliet, Bernard with Rose, Sun with Jin and baby--- Hugo with number 22.....BEN and all the others there too. Miles hits on Claire whose holding her baby. . . All those great moments.
Locke's van pulls up too close to another car--- the van door where his wheelchair goes opens and gets stuck again---- his wife moans, "John. . . " But John WALKS around the van and says, "I just hit the wrong button. We need to get a new car."
So, why not a happy for all???--- this will make us fans cry. I'm sure in those 78 minutes just before ALL died heroically on the Island.... I'd say give us fans a happy ending for all or most in LA X.
At the wedding, Jacob is standing looking-on in a Tux smiling and says to who's next to him--- "I told them than Ben is the only one where I took his Island memories away--- they will keep the secret"--- the camera pans next to him and it is MIB guy from last years beach scene also in a TUX. . . MIB says, "Looks like you did it again." Jacob replies, "Just progress.... That Snannon is HOT!!." END