It possibly depends on what their supply demand issue is. If they have plenty of parking - because the parking to rooms ratio is reasonable and a lot of people use Magical Express, there isn't any reason to charge DVC members to park other than corporate greed. If they discover that they don't have sufficient parking, then in order to get people to use ME, they may charge - ramps are incredibly expensive to build and have security concerns, I can't see many ramps going in at hotels just to provide ample free parking. They may also build an "off resort" free lot that you can catch a shuttle from (sort of like airport parking) for those that drive (and therefore don't use ME), but won't use their car regularly at Disney, then charge for parking at the resorts themselves.
They only have so much real estate to work with - and when you add units to a place like the Contemporary, you use up land that was used for already tight parking.
I suspect the first step however will be scanning your magic bands at gates - if you are a guest at that resort, you are fine. If you aren't, you'll pay - even if you are at the resort to dine or shop. No magic band, insert credit card. For most of the resorts with issues, non-resort guest parking seems to be a factor (BW, Poly, CR)