Thank you!
The best thing that could happen is for Protestants to become Catholics or at least to become more Catholic, and for Catholics to become less Protestant in their outlook and understanding of the faith.
A friend of mine, a former Lutheran minister who is now a Catholic and may be ordained as a priest in the not-too-distant future, makes the same point all the time. He constantly urges his fellow Catholics to strip away Protestant tendencies from their lives. He wants only the truth, the Catholic truth and nothing but the traditional Catholic truth. It’s humbling and inspiring to hear this come from a man who I know loves God with his whole heart and who also was a Protestant just a few years ago. God works miracles indeed!
Crossing the Tiber is two-way traffic.
I personally know Protestant pastors and elders who were once active and committed Catholics. These men are firmly committed to the truth as well and each felt that the Catholic Church perverted Biblical truth. I'm certain that their testimony would be just as strong and sincere as your former-Lutheran friend.