Yeah. MagicBands enable some significant datamining, and also I believe are part of Disney's solution to park efficiency management - so there's a VERY good chance that they are already saving the park significant amounts of money.
More importantly, most of the "magic" behind MagicBands is software. The hardware side of it is actually pretty old/non-exciting (other than, I believe, they had a lot of challenges making a "one size fits all" accessory - but that's more of a human factors challenge that can be reapplied to new hardware). Under the assumption they used one of the standard RFID protocols (likely NFC or something interoperable with it), the hardware is dirt cheap for both the devices AND for the readers.
So they might in fact be betting on trends in the smartphone industry going the way they are such that smartphones replace the MagicBands in the long term - it's just a software upgrade for their systems and if they're using NFC, the infrastructure is already there for Android devices. Android 4.4 and later replaced the embedded secure element for payment with host card emulation - this gave Google the ability to deploy some nifty security tricks for Google Wallet (geographically/time-limited "throwaway" credentials) but it ALSO gave the ability for any developer to write a card emulation app. So the infrastructure exists now for Disney to package up MagicBands in HCE form for Android devices. They likely won't since the iPhone hardware is crippled in this regard (even moreso than pre-HCE Android as you can't even implement reader apps on the iPhone, the NFC hardware is for payment only) but iOS might eventually improve here... Might - after all they STILL don't support Wifi Direct.