Nobody can commit themselves for an indefinite period, and you seem to choose to take the last part of that quote as relating to the first part. I see it differently.
Toyota has said it will build the next generation of its Auris hatchback at its Burnaston plant in Derbyshire.

The Japanese carmaker also said its Deeside factory in North Wales would build most of its engines

It goes on to say

In other words, it is firmly committed to the UK for now. But that commitment is not open-ended or unconditional. and

"With around 85% of our UK vehicle production exported to European markets, continued free and frictionless trade between the UK and Europe will be vital for future success." (Dr Johan van Zyl, president of Toyota Europe)

For now, Toyota is increasing its investment, and will build its new model in UK. Due to uncertainties it cannot make promises beyond these promises already made.