It's more than a little ironic that while the big two super hero universes have been stuck in a state of sliding stasis for decades, they have both been eager as hell to skip forward into the near-ish future to show how things turned out, (or, more likely, stayed roughly the same with a few random developments).
So while poor Franklin Richards has been trapped in adolescence for far longer than most current comic readers have been alive, there have already been numerous examples where we have seen a glimpse of a future where young Frank is all grown up, without having to bother with all that awkward stuff in-between.
Overall, Marvel seems more interested in skipping into tomorrow than its distinguished competition. (Although it could be argued that Kingdom Come is the most influential DC comic of the last two decades, with the DC universe moving in a direction to give that four-issue series continuity credibility, only to shift it into one of its parallel worlds.) And there have certainly been other glimpses of this universe, including the legendary Dark Knight Returns, a recent stab at a future for the Teen Titans, and, most notably, the Armageddon 2001 series, which made the slight error of actually putting a solid date on events, giving us possible destinies that are still in the future for the heroes involved, while technically taking place eight years ago.
But Marvel seems to have built up more possible futures for its characters, with almost every hero having their own outcome. These can range from various 'End' tales that the company was infatuated with several years ago, (some of which defied insurmountable odds by actually being rather good), to entire lines of comics.
While the search for new storytelling avenues made such tales a little inevitable, Claremont and Byrne have to take a fair bit of the blame. Their original Days of Future Past started off as a fairly inconsequential story at the tail end of their classic collaboration, and has grown to spawn an entire mini-genre of Marvel futures. The template is all there in that two-issue tale, with surviving heroes still battling evil and stupidity, a world forever changed and the usual random line-up of grave-stones. This little story ended up spawning a whole pile of X-tales that spiralled out of this timeline, with several characters making their way back into regular continuity.
Other Marvel creators seemed to have taken their fair share of inspiration from the Future Past, and have opened up a wild number of divergent futures. Some show up for an issue or two, (including as part of the various What If? comics) before vanishing into the timelines, while others, including Killraven's War of the Worlds future, (which eventually to led to the Guardians of the Galaxy timeline of the 30th century) and the 2020 where Iron Man gets some gnarly teeth and cogs added to the armour, pop up fairly frequently.
With the “real” Marvel universe continuing to chug along at a snail's pace, Marvel has even jumped into the future with both feet with entire lines of comics. The 2099 universe certainly had its occasional charms, (thanks mostly to Peter David's Spider-Man), but was too far removed from a recognisable Marvel world to be of much interest to most fans, eventually spiralling down to a fairly lacklustre end. The M2 line of comics had plenty of links to the current versions of the characters, but never really made it past a loyal base of readers, who somehow still kept Spider-Girl chugging along nicely for years, despite threats of cancellation every second Thursday.
Alex Ross and Jim Kruger have offered yet another version of the near-future with the incredibly dense Earth-X stories. While offering enough differences from normal continuity to make these tales impossible to align with the present Marvel Universe, it followed the well-trodden path of random deaths, falls from grace and eventual transcendence, familiar to anybody who has been interested in the final fates of their favourite men in tights.
Further into the future and there are even more possible outcomes for everybody. DC has had their fair share of flights into far-flung tomorrows, from the 25th century that produced Booster Gold to Abra Kadabra in the 64th, and the world of DC 1,000,000 in the eight hundred and something century. It has also produced the most successful and long-running glimpse of the future with the Legion of Super-Heroes franchise, although its ties to the modern world have frequently been its undoing, as slight changes to the current continuity produce massive knock-on effects for that happy bunch of teenagers.
Over at Marvel, the far future has also been touched upon, with the aforementioned Guardians of the Galaxy, as well as minor characters like Death's Head travelling out from the year 8192, or Kang from yet another version of the 30th century. Right down the end of the line, John Byrne came up with the sadly-unfinished Last Galactus Story, with the universe ending with the big purple fella cracking open and blasting away the universe with all that energy that he has been chowing down on for eternity.
But it's still the stories closer to home that resonate more, giving the reader a sense of closure to popular heroes, given them their Ragnarok, and avoiding the sheer banality that sets into any long-running tale.
Peeking into the future might provide the cheapest of thrills, but it also ensures all bets are off, and that anything could happen. Most importantly, they give these fine characters a chance to put their feet up, and put their never-ending sagas to rest.