Sure, demand for Disneyland will only increase in the future, barring some major socio-cultural shift that no one can currently imagine.
If they close the existing 1,200 space Pumbaa lot that is parked via brute force and then serviced by a rag-tag fleet of inefficient city buses and/or a 1 mile walk to the parks in January '16 and turn it into a 5,000 space structure with direct moving-sidewalk access across Harbor Blvd. to the parks that will be a HUGE IMPROVEMENT for 2018. That gains them not just 3,800 spaces, but a vastly improved customer experience.
In addition to the 2,000+ spaces for CM's they have just finished (Harbor/Ball CM lot) or just begun building (Katella CM lot expansion), there would be an additional 6,000 spaces by the time Star Wars Land opens by 2019-20.
Not doing anything is always an option, and TDA has perfected that strategy in the last decade. TDA appears to be changing their parking strategy abruptly now, and I'll take the extra 6,000 spaces by '18 over doing nothing for another decade.