Don't give a beep because they writers were horrible to their story and beep us over in the end.
"No talking from things that don't talk!" - Jaye Tyler

The set-up could just be, "Hey kids have I ever told you about that time that X happened?" Then flashback to 2016 or whatever and tell the story. Retcon some of the worse parts of the finale that need fixing to help the narrative and bam you have a season long story of How X happened. Next season is a new story. Or if it's just a reunion "movie" type thing it's a two hour story of X.

how though?
Only thing that would make sense is that we see the gang coming together after 2030 and then having flashbacks to untold stories that happened during the runtime of the series.
Im afraid everybody that hated the finale will be triggered by seeing Ted and Robin together though.