I don't think it possible to say what will happen with any certainty. The Brexit issue will have some 'natural' Tories and Labour supporters voting LibDem or Brexit Party. That turns the 'normal' modelling on its head and renders national opinion polls even less reliable than usual.

After the 2017 debacle the Tories have made their manifesto super cautious. That may yet prove to be a mistake as it allows Labour to make all the media noise with their massive tax/borrow/spend promises and NHS scare stories.