Tesla Gigafactory 1 in Nevada was once promised to produce up to 105 GWh of lithium-ion cells (and 150 GWh of packs, partially from imported cells) annually. However, it's at 35 GWh now, which was not an easy feat thing to achieve.
According to the interesting article in the Financial Times (paywall), Panasonic sees potential to increase the production volume from 35 GWh to 54 GWh annually, as the company recruited/is able to recruit more workforce:
“To build its team, Panasonic recruited chemical engineers from non-battery sectors and trained them to handle lithium-ion batteries. Now it has 3,000 people who operate the machinery and about 200 technical assistants from Japan to keep the plant running 24 hours a day, 365 days a year.”
“For us to move to [54GWh] should not be so hard. We now have the knowhow to do it in quite a high volume environment,”
We never really doubted that Tesla/Panasonic is able to increase the production volume (the problem was rather the rate of ramp-up and delays).
As Tesla's battery needs are expected to further increase after the launch of Tesla Model Y in 2020, The question is whether Tesla/Panasonic is willing to continue their partnership, at the 54 GWh level? Most likely the answer is yes.
The mystical, future Tesla-battery might require a careful market introduction, which is probably not a good fit for the high-volume Model Y, which is demanded as soon as possible.