Divayth Fyr is a young whippersnapper of barely 3000 during the time of the MMO.

The Dunmeri Triune is at the height of their power.

Will we be able to meet these and other people, do you think?
Would you like to or not, and why?

Personally, I hope that this will be possible, that they are represented as NPC's in the game.
But I also really hope they will be done justice, and established lore is adhered to as much as possible and fun.

I'd hope so! To meet one of the Direnni clan maybe? or Hlaalu again

Hopefully we will. On the other hand, besides the ones you mentioned, not a great number of famous Tamriel figures are alive during the time period, and I think that's probably intentional as well.

Thats true, we dont know a lot about that time.

Still, we know some things about the world, like that Bosmer cities are migratory trees.
Mannimarco is also around, so is the mages guild.
I hope that all these little things will be represented in the game.

Hjalti was second era, wasn't he?

He certainly was alive near the end of the Second Era. Whether he appears depends on how close the game is set to the Era's end. I think there's a strong possibility it will be set a century or so before Hjalti's birth.

If we should take '1000 years before Skyrim' literally then it will take place around 2E500.
Hjalti was born around 2E827.

We dont really know much about the fifth, sixth and seventh century of the second era, and I agree with you that its likely the game will be set during that time. Its a handy way to avoid conflicts with existing lore.

http://www.imperial-library.info/content/second-era is a timeline of the second era.