Senators have to run in non-sculpted jurisdictions, ones that almost always have at least some geographical/population density and ideological heterogeneity. To put that more concretely, it's hard to be a complete freak and win a Senate election. That's especially so if you're already in the House and taking votes - as a number of the GOP's top Senate prospects are. A number of those people looking for the big promotion from the House to the Senate next year are on the line for what just happened in the House and much more vulnerable than their House brethren to the beating being taken by the GOP brand. Even if they're not in the House, to get seal their party's nominations they'll need to be going full shutdown better to burn out than fadeaway mode through much of the year.
Dems are far from out of the woods yet. But it's looking at least somewhat more likely that Republicans will blow the third Senate cycle in a row in which they looked well positioned to retake the chamber.