Actually cars had existed for 50 years....the inter state highway system was the reason for their demise.
Oh this is a tough question. It is the inherent problem with the on-the-cheap design that DCA 1.0 was given. I say it has to stay as is without committing serious themeing errors. Cable cars cannot pass through PW as that area is themed specifically to Monterey bays cannery row(not SF). And red cars passing down the east side of grizzly peak, although the better option imo, would clash with grizzly peak, clash with wine country trattoria and clash with the view from that restaurant of PW! But hey Disneyland has a monorail going around a Swiss mountain and nobody bats an eye! So maybe we'd learn to love it. Its a very small park anyways compared to its much bigger brothers in Orlando. Hey Epcot is 4 times its size and doesn't have a park transit system!
World Showcase Buses at Yesterland
There was some spectulation that a Peoplemover-like transportation vehicle would run around Communicore, but I'm digressing, so back to the thread.
I like the whole idea of a Red Car Trolley Expansion or Cable Car Addition, it would be the answer to the Disneyland Railroad in DL.
Maybe I didn't say this earlier, but I think a Red Car extension should serve the same purpose it serves now, DCA's resident superfluous transport system. I think every Disney park should have one.
I like the idea of an expanded transportation. The trolley wires might not work all all the way to the pier but other modes of transportation would fit perfectly. The parade route should have some other vintage cars taking people up and down the route
If they were to run the trolley along the parade route, it could be incorporated into the show.
Adding buses and another trolley line would be great for people who can't walk a long distance but also would add color and kinetic energy to the place.