They won't be able to pass tax reform anymore than they could healthcare or immigration. The Repubs will likely lose full control of congress in the mid terms, not that they ever had it, and that'll be the end of their agenda for the rest of Trump's term. 
The Dems are good, they've been able to blunt Trump and his agenda through skillful use of the media, keeping his administration mired in non stop controversy and collusion allegations to the point where they're unable to pass anything.
Much like Obama's last 6 yrs, nothing but gridlock in DC.