How to see the future

[Mandrake]

Hi, guys!

Longer story
My party is getting heated up to start playing 5e, but we haven't finished this campaign in 4e yet, and they really like it. So we got to an idea that we continue the story arc starting from level 1 in 5e before we finish 4e and play parallel games. The idea is that 5e story is some 30 years after 4e story, where they can get a glimpse of what the world will be like. Also, the idea is that the characters from 4e are somehow seeing what 5e characters see (think and feel), each one of them being related to one future hero (of course, the same one they are playing).
So my question is: how would you describe it in game terms? Is there a ritual that can allow them something like that? Is there a powerful being? Who would that be? What other circumstances would that entail? I'm asking for both mechanical, RAW pointers, and creative ideas. Thanks a lot!

TL;DR
What are the best ways to tell the future, both mechanically and story-wise? Are there any powers, rituals or items that are related to seeing future? Is there any mention of someone or something that can see through time (e.g. Ioun can or somesuch)? Thanks!

[Laserlight]

What are the best ways to tell the future, both mechanically and story-wise? Are there any powers, rituals or items that are related to seeing future? Is there any mention of someone or something that can see through time (e.g. Ioun can or somesuch)? Thanks!

From a story aspect, Savras is the god of divination.

From a mechanical aspect, you don't want this to be something the players control; if they are the ones controlling it, they'll use it for something else. You know how PCs are.

Have them get prophecy from a madman. Have them see dreams. They find a small coffer, the sides of which are covered or painted to show The Heroes, and the coffer whispers to them. They find a document they need, but it's covered by that spell that conceals the real writing with a false one; the cover is a tale of the Heroes. A small girl tells them of the deeds, and when the players look away for a moment, she's gone.

[MKV]

I have always had a problem with impossible to modify predictions such as these. Namely the future world could look quite different depending on the characters actions. Consider the Archmage epic destiny from PH1 it explicitly states that there are many different options for the possible archmage all of which have a different impact on the world. Any actions the characters take especially at high levels will have major impacts on the way the world shapes-up.