Square Enix is already hard at work, releasing ports and remakes of their Final Fantasy titles on mobile devices, I'm guessing it was only a matter of time until we'd see Dragon Quest make the same transition.
Not officially announced for the US however, the Japanese market will be seeing mobile ports of Dragon Quest 1 all the way through to Dragon Quest 8, which the latter will seem like quite an impressive feat.
Dragon Quest 1 will be released this Winter in Japan, and the sequel will follow suit.
As someone who actually enjoyed Square's Final Fantasy mobile ports, despite their oddly sharpened graphics, I would be happy if DQ games made the jump to the US eventually. Here's to hoping