The last time that we had a situation like you describe was in the thirties when the New Deal was at its peak. The significant difference, of course, that the southern block of Democrats were almost all conservatives and they were able to block or damper some of the most outrageous progressive ideas.
If the Republican caucus were to shrink to less than 30 members, then they would have no influence on the floor and almost none at the committee level where seats are assigned in proportion to the size of the caucus. The political strength of any group is measured by the number of votes that they control. If you don’t have the votes, your voting block is impotent.
Nobody is talking about a caucus of less than 30 members.