Some regional airframes and flying will go away, while other, larger regional airframes will start replacing mainline narrowbodies.
Growth at any regional at the expense of the mainline partner might be good for one's career short-term via a quick upgrade, but it is VERY bad long-term...unless you intend on being a regional lifer. And regional airlines don't like lifers...they raise the average crew cost with each year of longevity, making them less competitive when compared to companies with lower average longevity.