I think this was more of a PR stunt than a serious business plan, I am guessing Model S owners are happy enough with the superchargers and their locations although I am aware that some of the super chargers are now getting busy so the answer is more super chargers, better place is still pretty fresh in the mind maybe too, not sure battery swapping is where its at.
I guess that building a battery swap station would require a large number of battery packs to be used. At the moment, Tesla are short of battery cells and all the cells they get are used for MS production. Hopefully, there will be a demo battery swap station built when the supply of batteries increases. I would guess Q4 this year or Q1 2015.
IMO it's all a bit of a minefield. There is the question of what to do with the swapped batteries. If they were all leased, it would be no problem. But they are currently all the property of the car owner, which makes it a bit of a logistical issue, especially if the owner is someone who really cares about their battery (see the threads about A B and D batteries on TMC for example) and doesn't want to get lumbered with an older/lower capacity pack!
There was a very good reason for Tesla to have built battery swapping and it had to do with the way that the Air Resources Board (aka California ARB (or CARB as those of you outside of my state know them)) provided credits for car manufacturers building "alternative" fuel vehicles.
At the time Tesla was demonstrating battery swap, car manufacturers got a larger credit for building vehicles which can be refueled to full in ten (I believe it was in ten) minutes or quicker (i.e. akin to a gasoline/petrol pump.). Therefore, battery swap provided Tesla with the most credits which it sold off to other manufacturers that will not make their alternative vehicle production numbers.
However, since then, the ARB has re-jiggered the credit system to de-emphasize this and to promote hydrogen.
Renault tried battery swap and failed miserably. Better place went bankrupt and the only production EV with swapping went out of production.
Renault took out battery swapping and added rapid charging to Zoe at the last minute. Kangoo was also supposed to get battery swapping, but that quietly went away.
How many people would agree to battery swapping if it means you can never own the battery? At least on the forums, there appears to be a large resistance to leasing the pack. I was the first battery lease customer at our Nissan dealer.
I think its an option if it can be done cheaply enough, I don't think you need to lease the pack you just need to be in warranty and the pack you get is tested and repaired to make sure its 100% good to go.