Well this is certainly unexpected.
According to DC’s Source blog this morning, the Flash is ending in May. “What?” you’re saying. Yeah, we’re saying it too. Isn’t there supposed to be a 13th issue? And why would the story end so soon?
The Flash has featured a myriad of trials since it first came back, specifically with heavy delays. The 9th issue, the last to come out, was supposed to be released in December, with the 10th originally coming out in January. As of now, the 10th and 11th issue will drop in April, with the final issue coming out in May with Flashpoint #1.
It’s a possibility that Johns, what with his new responsibilities, might have gotten a tad overwhelmed in writing both Green Lantern and this title along with the event Flashpoint. It’s a shame, really. The title definitely had longevity. It’s possible that the rush to get out another event “as big as” Blackest Night killed the Flash, but hopefully Barry will remain alive by the end of it. Who knows, maybe that long rumored Speed Force book will come out the other end of Flashpoint?
(via source)