If you see how the median yellow line moves up and down
I'd like to know more about who devised that yellow median that wanders all over the place.
Roberts is another Earl Warren. Ike once said Warren was his biggest mistake. When being considered for appointment, all of these jokers probably tell fairy tales about what their positions are, how they'd rule, etc. For a number of reasons, it's nearly always more difficult to uphold a conservative position than it is to sleaze and slouch into a liberal one. Just consider the two definitions. It's more difficult to live a life that is defined by stricter standards than it is to live one based on easy standards.
Here's the range of future possibilities for SCROTUS... For optimism, we'll assume Trump is reelected, all of these are before end of second term and all are firebreathing conservatives.
Current Court: 4-1-2-2. Four Commie garbage, 1 switch-hitting Chief Justice who always takes whichever side gives him most "legislate from bench" power, two untrustworthy at-best-semicons (Gorsuch and Kavanaugh), and two real conservatives.
Post-RBG: 3-1-2-3. If Roberts can strongarm Gorsuch or Kav to side with the Left on any given case, 5-4 with the doors blown open against us. If not, 6-3 nominally ours but so narrowly tailored it's as useless as a castrato's trousersalami. That's the BEST case, worst is one of the Ruesome Twosome flips making it 4-1-1-3.
Post-Thomas: Status unchanged.
Post-Sotomayor: At this point we're looking at a nominal 2-1-2-4, but my bet is Gorsuch and Kav would both move Left "to preserve balance" and Roberts finally rips the mask off revealing himself to be Zombie Earl Warren.
So we really need THREE replacements between the Left, Roberts (Damn you, Bush Leaguers!) and the Switches, plus a Thomas replacement to ensure we KEEP his seat. Unfortunately, thanks to Trump we're gonna be stuck with the two Switches for a long time...
I thought I invented the irreverent acronym, "SCROTUS" but maybe not. Nobody has a crystal ball, but all of these scenarios have a high plausibility factor.