You weren't addressing me, but I have a hypothesis. It doesn't directly involve Dems or Reps. It's the constituents. Discontent would have risen, possibly to the level of anti-Nam protests in the late 60s. That -perhaps- would have motivated more on the right to follow MTG into changing sides on this one issue.

Isn't that exactly what happened, though? Just on the other side? Constituents getting upset about the loss of important government services, leading a group of electeds to back away from the strategy of leadership and cross the aisle to reach a deal? It was simply Democrats, not Republicans, that were more motivated by the dismay of their constituents.

The problem with your suggested path to subsidy extension is that constituents weren't blaming Republicans significantly more than Democrats. Sure, a little bit - which was a better-than-typical outcome for Democrats, because historically voters have blamed the party that was trying to use the shutdown to obtain a policy goal. But for the most part, constituents weren't especially more likely to pressure "more on the right" to change sides than to pressure "more on the left" of change sides.

Then add to that the GOP has someone that can enforce party discipline to a degree the Democrats can't match. That's an advantage to holding the Presidency generally - there's someone who is both the undisputed leader of the party and has the ability to dole out a lot of rewards and punishment. But more specifically, Trump has a hold on the party's voters almost unmatched in recent history.

So, no - growing pressure wasn't particularly likely to bring about compromise from the GOP side moreso than the Democratic side. They just weren't being blamed enough for the shutdown. More than one would have expected from past precedent, but nowhere near enough for this strategy to lead to a GOP fold.