No, The Event isn't coming back. Yes, rumors are swirling through the Internet ether about SyFy possibly picking up the show, but the channel has denied such reports.
Deadline started the about two days ago, and Entertainment Weekly ran with it. After that it spread from news sites to fan sites around the web. No one bothered to get confirmation, however. It was just a rumor.
Apparently Deadline reporter Nellie Andreeva claimed she "[heard] talks" of such a possibility, going on to say that she had also heard that the cable station was attempting to determine if it could afford to produce the show.
That’s all well and good, a rumor is a rumor, but as these things tend to happen, it was soon being reported as fact, and apparently the official SyFy Channel Twitter feed was getting some requests for confirmation from fans, because an executive at SyFy, Craig Engler posted this to the feed:
"To answer some questions I've been getting, at this time we have no plans to pick up The Event."
So, it's not true; not yet anyway.
The story is still spreading as if it is, however, probably because it seems like a good match: defunct sci-fi show which was cancelled for having only a million or so viewers and a cable station which specializes in sci-fi shows, for which a million viewers is a very good number.
Unfortunately for fans of The Event, SyFy likely realizes that they would not be able to keep those numbers. Even loyal viewers would lose the show in the transition and much more than half of the viewership would disappear.
In addition, the writing would likely suffer - not that it was incredible to begin with - because none of the same creative team would be on the show. SyFy would bring an all new team to the board, and would likely even lose some actors who simply aren’t interested in doing cable.
Finally, the budget is likely not there. The Event was building itself up to some storylines which would likely be expensive to produce properly, and a station like SyFy only has about a fifth of the per-show budget that a major network can provide.
(See Sliders for a good example of precedent on all this stuff.)
If any cable network wants to take up The Event, they would have a lot of challenges ahead, and if every single piece doesn’t fall together perfectly, they simply won’t do it.