Yes.
They are not the tares. The parable of the tares is about there being people inside the Church that are not living right before God’s eyes, and who will therefore not enter Paradise at the Judgement.
The new vines in my metaphor are those outside the Church. Can there be any good fruit outside the Church?
Here is a metaphor I like:
Christ is the Physician and the Church is the Hospital He established. We have the sacraments, scriptures, patristic writings, liturgy, icons, hagiography, etc. These are the medical manuals, equipment, supplies, medicines, etc. that aid the sick in recovering from the illness of sin. Now, there are people outside the Hospital too - outside the Church. They lack the fullness of the aid found in the Hospital, to various degrees. Maybe some have quacks they see. Maybe some have folk remedies. Maybe some just hope for the best and wing it. All, however, lack the fullness of aid found in the Hospital.
What are we in the Hospital to do? Of course we will invite all to the Hospital. (There is ample room!) Those institutions and traditions outside of the Hospital are not part of the legitimate institution. Does that mean the Hospital produces all healthy people? Of course not. The Hospital is designed to facilitate the healing of the sick if they follow their treatment regime. People are people though, and they are not always faithful to what they should do. When you’re ill, not following your treatment regimen can be a recipe for disaster! Sadly, not 100% of those Hospital patients will recover.
And what about those people outside the Hospital? Will they all necessarily perish? No, I cannot make such a bold claim. We cannot know for sure what will happen to those people outside of the Hospital, but surely survival is not impossible! How will they be healed? We can’t know. The Physician, though, goes where He wills. Perhaps He treats some of those people too, despite their refusal to enter His Hospital. We don’t know. All we know is that all people are supposed to be in the Hospital. He has revealed some knowledge of how things work inside His Hospital, but what happens outside it is a mystery. It is not for us to know. We invite all to the Hospital and oppose those persons and institutions that would draw people away from the Hospital. If someone refuses to come to the Hospital, the most we can do is hope for the best.
At the end of the day: the Physician has mercy on whomsoever He wishes to have mercy.