Dire Bare
Legend
Well said. Time travel has been an especially big feature of Dragonlance. Raistlin's time travel was a key element of the Dragonlance saga. There was a whole 3.5E sourcebook about time-travel in Krynn: Legends of the Twins: http://www.dmsguild.com/product/3252/Legends-of-the-Twins-35?affiliate_id=2126
Mystara has the Comeback Inn - a time machine which takes the characters to and from the Age of Blackmoor. And also The Nexus from the CM6 module, whereby the party can visit any time or alternate world.
Timetravel is, or could be, a prominent meta-setting for the D&D Multiverse.
Dragonlance is a good example, as it did introduce time travel rather early in its life as a setting theme with the Legends trilogy, and there was a short story collection that included several "what if" alternate timeline scenarios. Dragonlance did a good job using time travel as world-building in the novel series, although I'm not sure how well it was ever used in the RPG books.
The Comeback Inn from Mystara, however, is an awful example. This macguffin allows the party to travel back in time from their medieval fantasy world called Mystara to the ancient, distant past medieval fantasy world called Blackmoor. It's like traveling back in time from Greyhawk to the Forgotten Realms. I'm a huge Mystara fan, and I hated the ridiculous shoehorning in of Blackmoor into Mystara's "ancient past". Once you get past the stupid time travel element, the adventures were interesting on their own however.
The Mystara Hollow World RPG supplements at some point touched on time travel, although I don't remember much about it. I do remember the "plane of time" being described as a green river, somewhat differently than Chronomancer described it.
I liked the Chronomancer supplement from back in the day, and I can see working a time travel element into a specific adventure idea. But having time travel be a "meta-setting" or the main shtick for a campaign? No thanks. I don't think that's what Wizards is hinting at here at all, and I'd be disappointed if they were.