Changing one of the subs important parameters like a driver or enclosure size will impact everything else significantly. It would be much more difficult to match the EP500s smooth FR and extension even with the XLF technology.
I wouldn't be surprised to see the sub line expanded.
Mini versions of the 500 using smaller enclosures and drivers would make alot of sense but the FR range would be smaller if you want it linear which is Axiom's hallmark.
I wouldn't be lulled by other manufacturers' claims of uncomporomised extension for the sake of sub 20hz response. Those subs are not usually linear especially compared to an Axiom sub. With other subs I've owned that extension usually comes at the price of less distinct bass and falling FR from 30hz up. Not a good compromise.
