depends if you pre order from game stop then yes pre order the regular, then when the the limited is announced which im sure there will be one then upgrade. if you pre order from amazon im not sure if you can upgrade.
I wanted a Collector's Edition at first, but now I doubt I'll change my pre-order to it should it be announced. It'll just include some plastic crap that'll gather dust in my room. The poster is all I really wanted.