Time will tell I guess. To get Tesla to commit to another technology completely (I'm a little confused as to if we are now talking of a new battery chemistry that does not involve Lithium, or if we are talking about a Gigacapacitor) at this point in time will be very difficult. As you know they will break ground next month on the first site and expect to be producing double the current global production of batteries in Whrs perhaps already end of next year. So whatever technology you have in mind would have to be really mature.
3 years is the target for production unless that has changed. Things always take longer than planned, so the end of next year would be a real shocker if it happened.
I'm not limiting the technology possibilities to either batteries or capacitors, or maybe both types produce advances beyond Li-ion. But, given the amount of time Li-ion technology has been on the market, it's a mature technology and its days could very well be numbered. And, I would suspect that the Engineering Dept at UT has access to a lot of inside information, both within their labs and from outside companies they do consulting work for, that they can't release to the public.