Again, I really think people should consider what figment_jii has been saying: MagicBands and FP+ are two separate things. They could bring the former to DL and not the latter.
I have a slightly different perspective, because I work in the financial industry, and have seen the tremendous trajectory of mobile and hands free payments. There's plenty of data suggesting people spend more when they don't have to have a card or cash (I know my Starbucks spending went WAY up when I started paying with my phone). Disney is considered a leader in that they're willing to invest NOW in a technology that will pay dividends down the road. The ability to link a credit card to the band has always been a goal, even though they're not quite there yet.
And personally, if all I had to carry into the parks was my phone and a wristband, I'd be one happy camper. Think about the kinds of things that could be on the band and make a DL trip EASIER:
*AP cards and tickets could go away
*PhotoPass and ride photos activated with your band
*
DAS cards attached to your band (no more cheating or people writing in new times on their cards)
*Pay for your meal or purchase with the band
*No more forgetting your AP discount if you have an AP and pay with the band; it could be automatic
*Technically, they could keep the STRUCTURE of the current FP system while just using a swipe to load it.
*Faster entry and less bag check
Point is that this technology is incredibly adaptable, and doesn't have to mean the end of DLR as we know it. If the lessons from WDW are learned - and the unique demographics of DLR are taken into account - the technology has a lot of potential.
(PS: They're going to have to upgrade all the credit card machines in late 2015 and early 2016 anyway when the United States goes to CHIP and PIN technology rather than magnetic credit cards. So, this is more likely the impetus for them implementing MBs around that time.)