They are stopping it after 4 volumes, it did have a decent fan base on the English manga sites, but I can't say I'm unhappy it ended. I personally liked the novels and the anime a lot better, something about the manga art I didn't really enjoy. Well it may not have been bad, mostly personal interest. Anyways, means the rumored art on some sites of a possible "season 2" weren't for the manga. If it's authentic, my hopes for a season 2 anime are raised.
I agree with ZeroXSEED that it isn't surprising, considering Media Factory gave the Infinite Stratos rights back to the maker. Anyhow, I think I saw somewhere that Media Factory kept the anime rights. Sorry, if I repeated something, just skimmed this thread and wanted to join in the discussion.