This week is Comic Con International: San Diego, and you know what that means: plenty of big announcements geared at exciting fans.

You know what else it means? For the next couple of days before the convention itself starts properly, there will be pages upon pages of rumor and speculation about what those announcements might be.

Today sees one of the biggest and juiciest such rumors we've seen in a long time: Bleeding Cool claims that they've got a source alleging Batwoman, Oracle (Barbara Gordon), and John Constantine are among characters expected to swing by Supergirl, The Flash, Arrow, and DC's Legends of Tomorrow in the near future.

Recent contracts for Wentworth Miller and John Barrowman have seen the actors sign on as "regulars across four shows," allowing for the possibility that Captain Cold and Merlyn might show up anywhere in the Greg Berlanti-produced DC TV Unvierse, rather than just appearing on The Flash or Arrow, for instance.

Such a contract has reportedly been offered to John Wesley Shipp, TV's original Flash, whose recurring character Dr. Henry Allen died during The Flash's second season, only to see the actor "brought back" as Jay Garrick, the Henry Allen/The Flash of Earth-3. He appeared in the season finale of The Flash, and since then Shipp has told fans at conventions that there were "big plans" for the character going forward but that's all. Given the fact that in the comics Jay is a founding member of the Justice Society of America, and that that JSA is a key part of the Legends of Tomorrow plot in its second season, it wouldn't seem unreasonable to think Shipp might have at least a guest appearance there.

The report also suggests that one of those deals may be open to Matt Ryan, who played John Constantine on Constantine before it was cancelled, but it's qualified with "if that show performs well enough streaming on CW Seed," which feels more like speculation than the rest of the piece.

Other claims made in the Bleeding Cool piece are that while there's an outside chance they might be able to work out a deal with FOX to get Bruce Wayne/Batman to appear on one of the shows at some point, Kate "Batwoman" Kane will likely arrive in National City for a Supergirl guest spot, where she will play off her ex-girlfriend Maggie Sawyer (the two were engaged in the comics, but as on TV, Sawyer has recently been returned to the Superman family of titles, where she originally appeared in the '80s). So, too, will Barbara Gordon, as Oracle, not Batgirl, with the dynamic between Barbara and Kate being akin to the classic Birds of Prey stories with Oracle and Black Canary.

The hope, the report asserts, is to launch a fifth DC Entertainment series, giving The CW a DC superhero show every night of the week.

All of these are pretty fantastic claims, but given the track record Bleeding Cool tends to have with DC scoops, don't discount them. With a little luck, fans will get a sense for whether some or all of it will come to pass this week at Comic Con.