That's not really relevant, though.
In the case of a dub being produced, all it would likely be is NIS goes to the Japanese company or committee and asks for the rights to create a dub, to which the committee replies "sure, whatever, so long as you don't do x or y" (paraphrasing here, of course). They may not even need to do this as it may have been part of the original license agreement.
On the other hand if Yen Press were to seek the rights to Toradora for one thing it would be an entirely new license agreement. For another, Dengeki Bunko would likely turn react with a "why would you want to license that? How about all these lovely ongoing series that we've got? Or perhaps this one that's just about to end?" If it hadn't finished as well (albeit in this case only a little over a year ago), they would probably also insist that they release Golden Time first/as well/instead.
Unlike with anime, where fears of reverse-importing mean that older anime can actually have an advantage over newer ones in terms of getting the rights abroad (the Japanese want to keep them back at first), when it comes to manga and, particularly, light novels, the Japanese rights holder will want to push their newer titles, rather than one that was a big hit the best part of a decade ago, but which (as far as Japan' is concerned) is been and gone.
I'm not saying it's impossible, mind - it's probably no less likely than OreGairu getting a license was, and that happened...
One thing you can be confident of, though, is that the anime getting a dub does nothing to increase its chances.