I wouldn't mind Tommy's story. We see him at the very start, we know he joined the fireflies, had a falling out with Joel and then left the fireflies. There's a rich story in there. Can't fill in the whole 20 years in one game, but the essential year when Tommy became disillusioned with the fireflies and then went to form his own community.
OTOH, there's no reason we can't pick up with Ellie a few years down the track, part of Tommy's crew and Joel dead, or maybe missing. Joel could turn up later in the game as an infected. Could go all Fear the Walking Dead and go to a completely different part of the country with an entirely new cast.
I hear there's a "conspiracy theory" that TLOU and Uncharted happen in the same universe, obviously Uncharted pre-dates TLOU. Would be cool if an 80-year old Elena or Chloe turned up in TLOU2. Not as a significant character, perhaps not even named, but with the right look and same voice actor, if they can put on an old-person voice.
It's going to be hard to make that emotional connection like in TLOU a second time. So we'll see if ND can strike twice. Repeating the UC formula is much easier than repeating the TLOU formula.
One thing that gives me a bit of confidence in ND is that if they're not feeling it, they won't mnake it. I remember an interview from a few years back where they said they worked up a whole bunch of ideas for Jak 4 but nothing was coming together, so they dropped it. This is good and mature decision making, so I think if they're not feeling TLOU2 they won't force themselves to make it no matter how many people demand it.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."