True for the moment. But look at the current political landscape, the prime players and the inclinations of the emerging voters. Not ever? How about "Not Yet".
Hillary most assuredly deserves a seat on the USSC because notwithstanding the recent greater popular vote - Trump and the Russians somehow illegally denied her the victory. (snort)
The Democrats are openly calling for SCOTUS to be expanded to 13 or 15 judges so that they can pack it with Progressives and begin the express rubber stamping of their agenda.
In that scenario giving a seat to Hillary as her consolation prize is not beyond the realm of possibility.