Yeah, I'm pretty darn confident that Supercharger capability isn't on the table. Too much has to change. Too expensive for so few cars.
My biggest hope is for an OPTION to buy a future battery pack (no need to make it now!) at far lower prices. That should help with Roadster resale values AND give Model S buyers more confidence.
I think that ChadS has the right way of valuing what gets done for Roadster owners. It's not how many of the widget can be sold to Roadster owners - it's what it says to the next generation of owners about how their car can evolve later in time. We can wait several years for the initial Model S fleet to age, and then come up with something that seems straightforward like a battery upgrade, and just hope that it comes along, and learn THEN how upgradable these early Model S's are. We can all think that it's straightforward and easy to upgrade the Model S's, and I think we can agree that on the surface, it should be easier than something like that would be for the Roadster.
But if Tesla steps up in 2014 with something of that scale for the current Roadsters, the ancillary goodwill across the entire Tesla owner community will be huge. Like move-the-stock-price huge.
I'm voting battery - use the current battery box for a Roadster and "fill" it with Model S chemistry batteries. There will be firmware updates required I'm sure, but the change in chemistry takes the roadster from ~50 to 80 kW sized battery. Do that, and now its running around out there in the wild for everybody to see - it's not just theory, it's real. (Crazy notion that the Roadster battery has almost as many 18650 cells as the Model S85).
That's what would be exciting and cool to me. A new brake option - not exciting or cool.
What I really want to see is the combo talked about by others - updated battery chemistry, liquid cooling for the PEM, maybe liquid cooling for the motor, DC hardware bypass, Model S style plug, firmware that keeps everything happy, and Supercharger access. That would be a technology game-changer, not for what it does for the Roadster owners (all 2500ish of us), but what it says can be done for the Model S. I also know that it won't be easy and it won't be cheap.
The straight battery chemistry swap, which also won't be cheap, would still fall into the exciting and cool. Even if the performance doesn't change, charging to ~170*1.6 = 272 Ideal Miles for a standard charge each day; that'd be cool.