Probably a typo. If they can do 100 gigabytes now and they're saying that's not the limit, it doesn't make sense for them to say their goal is just 25 more gigabytes. I think Professor Tsai meant their goal is a terabyte.
But the article is saying we're not going to see it because "the market isn't ready for it". In other words we the consumers will have to plow through the next two generations of formats (probably blu-ray at 30GB and then something newer at 60GB) before we see 100+ GB.