SLS was already made redundant when the Falcon Heavy flew.
'Let’s be very honest, We don’t have a commercially available heavy-lift vehicle. The Falcon 9 Heavy may some day come about. It’s on the drawing board right now. SLS is real.' - Charles Bolden
Note the reason given here isn't that the Falcon Heavy didn't have as large a payload capacity - that excuse came after it started flying years before SLS, because apparently we're supposed to pretend things can't be assembled in space over multiple trips rather than sending up a multi-billion-dollar rocket.
I'm just wondering what the excuse for keeping SLS around will be after a cheaper vehicle that can beat its payload is here. Jobs, for sure. What else?