Yes I believe there will still be maintenance. I have spent more on maintenance/upgrades for my Roadster than my last 5 cars and 500,000 miles combined. It is new technology and there will be bugs to be worked out and there are still brakes, cooling systems, A/C and the host of other systems in the car. I think that EV's will reduce car maintenance but it will be far from eliminated.
I'm not sure you can really use the Roadster as an example because there is so much that's really new with a company that was new. If EVs get to be a substantial part of the automobile population, they will also be far more robust. To take your points:
Brakes -- I expect the brakes to last much longer. My Prius still has the original brakes at 139,000 miles and I expect it may be 180,000 or more before they require replacing. An EV shouldn't be any different.
Cooling systems -- You change the fluid at 100,000 miles and then every 50,000 miles. Not much to do there and no real incentive to have it done that the dealers.
A/C -- The electric A/C almost never requires service. I've never had anything done to mine and I'm in Texas where A/C is a way of life. I can recall that my Dad's 50's and 60's Lincolns always had A/C problems (among other things) but it's very rare to have A/C problems these days--even with the engine driven ones.
Now compare this to the ICE which requires regular oil changes, valve adjustments, spark plugs, etc. or the automatic transmission. More importantly because you are doing this maintenance three to four times a year, there are four chances to tack on additional items, compared to one chance on an EV.
Now I don't doubt that the Model S will cost more to maintain then the Prius (for the record, I've spent $9,916.87 for maintenance and tires over 139,286 miles in 106 months) but the mechanical side of the Model S should be mostly trouble-free (If it's not, buyers after the first year will dry up).