“As the President has made abundantly clear, the US is withdrawing unless we can re-enter on terms more favorable to our country.”
That statement, from @LWalters45, is a good reminder that Trump has always left this door open.
Seems pretty clear that the Trump team is engaged in negotiations to stay in the Paris Accord—just as Trump has said that they were close to completing negotiations for amnesty (that he says isn’t amnesty).