Yeah, the percentage of PDP members who wiuld vote Republican if PR was a state could be 20% or 80% or any bumber in between; one would think that the historical ties with the Democrat Party would disappear soon, and that voters who want more local autonomy and lower federal taxes would be more at home in the GOP, but it would be a fool’s errand to make a prediction. We know how well those predictions turned out in 1959 (when AK and HI were admitted pretty much in tandem, since AK surely was going to be a Democrat state so it was only fair that obviously Republican HI be admitted as well).
But we don’t know how many NPP members would be Republican, either (and preference polls won’t help, since they don’t vote for persons running as Democrats or Republicans, except every four years in the presidential primaries).
You don’t think a POTUS referendum would be useful? Could the results be that far off from what they would be in a real election?
However, you do make a valid point that Puerto Rico is a wildcare as far as how they'd vote if they attained statedhood, and Congress got in completely backwards in predicting Hawaii would be a GOP state and Alaska would be a RAT one.
I think we can safely predict DC would be solid RAT if it ever attained statehood, however. A RINO managed to win one seat on the DC city council a few years back, but I'm not impressed. They're so far left in their Presidential voting patterns, they make Massachuttes look moderate.