The Jan 6 Committee says they welcome further Secret Service testimony under oath.
If the only things they dispute are (a) that Trump grabbed the wheel and (b) that he assaulted one of the Secret Service guys, then the rest of her testimony is still plenty damning.
If they deny talking to her about the drive at all, that would be shocking. It also seems rather unlikely.
And... there is not yet news about when their additional testimony might occur, which I would have expected, all things being equal.
ETA: Mick Mulvaney, Trump's former Acting Chief of Staff, said he believes Hutchinson's testimony.